Intestinal Problems in Gynecologic Surgery

The gynecologic surgeon must be familiar with the basic principles of intestinal surgery and be prepared to deal with problems such as intestinal adhesions. In addition, he should be prepared to identify problem areas during the course of these operations and, thereby, significantly reduce the likelihood of technical accidents or complications.

He should also be prepared to deal with technical accidents that involve the small and large intestine and to handle situations where unavoidable injury occurs. Although most postoperative complications are avoidable by adherence to standard and accepted surgical practice, the management of these complications is an important part of the postoperative care of the surgical patient, and a successful outcome may depend on skilled management.

In general, a brief evaluation of the gastrointestinal tract is sufficient in most patients undergoing gynecologic surgery. The more invasive the procedure, however, the more thorough the preoperative evaluation should be. Any patient who acknowledges a history of peptic ulcer disease, intolerance to certain foods, change in bowel habits, rectal bleeding, or intermittent, crampy abdominal pain or distention should have a careful evaluation of her gastrointestinal tract. For instance, those complaining of upper abdominal pain, especially related to meals, or those with a history of ulcer disease or with recurrence of symptoms should be evaluated with an upper gastrointestinal series and gallbladder ultrasound. Gastroscopy may or may not be appropriate, depending on the identification or high suspicion of a gastric or duodenal lesion. Similarly, patients with rectal bleeding, cramps, or otherwise unexplained abdominal pain should have a sigmoidoscopic examination and a barium enema, and, in some instances, a small bowel series and colonoscopy may be appropriate. Any positive preoperative finding in such a patient should be thoroughly evaluated, and the overall treatment plan should be revised according to the findings. A medical or surgical consultation may be appropriate in these patients. In the absence of such a history or specific symptoms, this workup is neither appropriate nor necessary.

Patients who have had multiple previous abdominal operations are another group who have at least the potential for postoperative bowel obstruction. These patients should be regarded at high risk not only for intestinal complications but also for infections and other types of complications.

Preparation of the patient for major gynecologic surgery usually is complemented by the use of a mechanical bowel preparation, such as an enema, to evacuate the colon as much as possible. If a patient is unprepared, the impaction of hard feces may complicate recovery and be associated with crampy abdominal pain. Additionally, any preoperative barium studies should (ideally) be performed at least several days in advance of an operation so as to allow the patient to fully evacuate the barium. Barium in the colon can become inspissated and rock-hard, and, under rare conditions, can even cause colonic obstruction necessitating surgical intervention. An abdominal operation can produce paralytic ileus and further compound this problem of barium impaction. For this reason it may be prudent to obtain a plain abdominal radiograph prior to surgery to determine whether any barium persists.

If involvement of the rectum, sigmoid, or some other part of the colon is anticipated in a surgical procedure, a 24-hour outpatient preparation is considered adequate. A potent laxative, such as magnesium citrate, is given orally on the day prior to surgery. In addition, a combination oral antibiotic is given as follows: neomycin, 1 g, and erythromycin base, 1 g, are each given in three separate doses at 1 pm, 2 pm, and 10 pm of the day prior to surgery.¹ An alternative antibiotic regimen uses metronidazole (500 mg) instead of the erythromycin, which in some patients causes nausea and vomiting.² Since this preparation frequently leads to water and electrolyte depletion, it is prudent to hydrate the patient adequately with electrolyte solutions in the perioperative period. When a rapid prep is desired, instead of a laxative, an oral, intestinal lavage type of preparation can be used. In a widely used bowel preparation, the patient drinks 2 to 4 L of a polyethylene glycol solution^3,4 on the day prior to the operation, in addition to the oral antibiotics. In addition, tap water enemas can be administered in the ambulatory department prior to the operation. Commonly, intravenous preoperative antibiotics are also given, employing a drug or drug combination effective against both aerobic and anaerobic bacteria. There is evidence that parenteral antibiotics given alone, in addition to the mechanical bowel preparation, are as effective in minimizing the incidence of infections.⁵ Consequently, the mechanical bowel prep at home, plus intravenous antibiotics given just prior to the operation is regarded as effective prophylaxis.

In certain patients with reflux esophagitis or active peptic ulcer disease, preoperative and postoperative antacid therapy is desirable. Ranitidine may be added, in a dosage of 50 mg IV every 8 hours, to decrease gastric volume and acidity. Alternatively, antacid may be administered pernasogastric tube in patients at risk for a pH lower than 4.

Exploration of the Abdomen

Exploration of the abdomen is an important part of any abdominal operation, and it should be done during a hysterectomy or other gynecologic operative procedure that permits such exploration. Systematic exploration of the abdominal cavity should include examination of the liver and its surfaces for possible metastatic or inflammatory disease. In doing so, it is important to handle tissues gently and to remove any powder from gloves, so as to minimize the formation of adhesions. In young to middle-aged women who have been on oral contraceptives, it is important to examine the liver for possible liver-cell neoplasms. Next, the gallbladder should be examined, if at all possible, since gallstones are prevalent in women. Next, if possible, the pancreas, esophageal hiatus, spleen, and kidneys should be palpated. At this point, adhesions involving the small bowel may be lysed, since it is difficult to explore well in the face of adhesions. When adhesions are dense, however, and freeing these adhesions is not a necessary part of the operation, exploration of the area involved is not appropriate. It is generally difficult to examine the colon thoroughly, but a brief examination of the ascending, transverse, and descending colon can be performed if indicated. In the vicinity of the sigmoid, one may find adhesions in patients who have had a history of diverticulitis. If one is using a previous abdominal incision, it is not at all unusual to have small bowel or even colon adherent to the incision: Consequently, in performing such an incision, one must take special care to avoid inadvertent enterotomy. Probably the best technique to avoid entering intestine that is adherent to the incision is to place the posterior rectus sheath and peritoneum on traction with Kocher or Allis clamps. This makes the adhesions between the small bowel or colon and the peritoneum fairly taut and also allows the surgeon to divide these adhesions under better vision. An alternative is to select an incision that is at a distance from previous incisions, if possible.

Intestinal Complications

ADHESIONS.

One of the most common complications that can occur during an operation such as abdominal hysterectomy is an enterotomy involving small bowel or the colon, usually the sigmoid because of its proximity to pelvic structures. This injury occurs principally during the lysis of adhesions, and although sometimes unavoidable, it usually is a preventable complication. When enterotomy occurs during the division of adhesions, it usually results from tearing the serosa when using blunt dissection or cutting directly into the lumen of the bowel during sharp dissection. There is no single best method of dividing adhesions, in spite of dogma to the contrary. In some situations, particularly when the adhesions are flimsy and are torn apart easily, gentle blunt dissection is the safest method. In other situations, when adhesions are dense and, especially, when important adjacent structures such as the urinary bladder are involved, blunt dissection or pulling on the small intestine results in tears of the bowel or adherent viscus. This happens primarily because the tensile strength of the adhesions exceeds that required to maintain bowel or other visceral seromuscular layer intact. Consequently, when adhesions are dense, it is generally safer to use a sharp method of dissection. The immediate recognition of enterotomy is important because if the operation is terminated without closing the defect, peritonitis will occur in the immediate postoperative period.

INJURIES TO THE SMALL INTESTINE.

Injuries to the small intestine can result during gynecologic procedures ranging from dilatation and curettage to total abdominal hysterectomy. Newly introduced laparoscopic and hysteroscopic procedures (such as laser-assisted endometrial ablation) can also result in intestinal injuries. For example, trochars, cautery, or lasers used in these procedures can produce intestinal injuries, and sometimes these injuries are not immediately apparent at the time of operation. A patient with such injuries may present with postoperative ileus, compounded by signs of peritoneal irritation, elevated temperature, and leukocytosis. Early re-exploration in these situations can be life-saving.

Ordinarily, once recognized, small bowel injuries can be dealt with in a straightforward manner. Serosal tears represent weak points in the small bowel. If obstruction develops postoperatively, these weak spots may perforate, leading to peritonitis or enterocutaneous fistulae. If serosal tears are few in number, they can be oversewn with either an absorbable or fine nonabsorbable 3-0 or 4-0 grade suture. On the other hand, if the serosal tears are numerous, and if one is satisfied after careful inspection of the entire length of small bowel that the tears do not include the mucosa, an alternative is either to leave the small bowel alone or to perform a resection. Through-and-through injuries are best treated by suture repair. These are usually evident in that bilious material can be seen emanating from the area of the small bowel injury. Generally, a single or double-layer closure is satisfactory. A single layer of running absorbable suture followed by an outer layer of interrupted 4-0 silk or teflon/dacron or, alternatively, a single layer of interrupted nonabsorbable sutures is quite effective. It is most prudent to repair the defect in the small bowel in the transverse direction (Fig. 1). If the laceration is long, or if multiple areas are involved, one should consider a small bowel resection. A resection can be done in a number of ways, but first, the two areas to be outlined are clamped to minimize the amount of intestinal contents that spill into the abdomen (Fig. 2A). An additional precaution is to place moist lap pads on either side of the small bowel, so as to further minimize the chance of spillage into the abdomen. A small V-shaped defect is constructed in the mesentery by first incising the peritoneum on both sides. Then the vessels in the V can be clamped, divided, and ligated so as to completely excise this V in the mesentery. When this is accomplished and the two ends of the bowel are freed over a distance of approximately 0.5 cm from the edge of the clamp, the anastomosis is performed. Although the tissue that is enclosed in the clamps can be included in the anastomosis, it is clear that healing of an anastomosis is enhanced by using noncrushed, viable tissue in the anastomosis. Therefore, stay sutures are placed between the mesenteric and antimesenteric segments of the two limbs, which are then pulled together and the tissue excised by sharp dissection just below the level of the clamp on each side (Fig. 2B). Next, either a single- or double-layer anastomosis can be performed.

A single-layer anastomosis of the inverting or approximating type can be performed by using Lembert sutures that encompass the seromuscular layer in its entirety. These sutures are placed circumferentially 5 mm apart. When one side is sutured, the anastomosis can be turned over and the other side can be done. The mesentery is then closed with a running suture so as to eliminate the possibility of an internal hernia.

Similarly, a two-layer anastomosis (Fig. 2C-E) can be done by closing the entire thickness or just the mucosal layer with a running absorbable suture such as chromic catgut or polyglactin and then using an outer layer of interrupted Lembert sutures of material such as 4-0 braided teflon/dacron or silk. As in the single-layer anastomosis, the mesenteric defect is closed by approximating the peritoneal edge of the mesenteric leaves using a running or interrupted suture technique. It is important not to include any mesenteric vessels in the bites taken with the needle, since this can result in a mesenteric hematoma that might compromise the blood supply to the anastomosis and lead to an anastomotic breakdown.

Under certain circumstances, it may be necessary to avoid an anastomosis altogether. For example, when the small bowel injury occurs in a patient with massive peritonitis, any intestinal anastomosis is hazardous and construction of such an anastomosis may be followed by suture line infection, with breakdown of the closure and recurrence of peritonitis due to the intestinal fistula. On the other hand, minimal and, especially, localized infections in the peritoneal cavity do not necessarily preclude the use of such an anastomosis or closure. An anastomosis may also be hazardous in the patient with longstanding bowel obstruction. In such a situation the fecal spillage that may result is infectious, especially when gangrenous segments are present, and occasionally, it may be prudent to perform an ileostomy or jejunostomy rather than an anastomosis. In addition, it may be desirable to perform an ostomy rather than anastomosis when an operation has been unduly long and it is important to save time: In the patient who is deteriorating, a simple stoma is more quickly constructed than is an anastomosis.

A stapling technique may be used instead of sutures to perform a small bowel resection and anastomosis.⁶ This is both a rapid and effective technique, once mastered (Fig. 3 and Fig. 4). Both sides of the bowel are divided with a stapling device (GIA ™ for example), which staples and divides the two ends at the same time (Fig. 3A). Next, a small portion of the staple line on the antimesenteric corner is excised on each end of the bowel to be anastomosed (Fig. 3B). Another identical stapler is introduced into both ends and is fired (Fig. 4A). This results in a side-to-side anastomosis, and the final step is to close the hole that results with a TA ®-type stapler, which staples but does not divide any tissue (Fig. 4B). Excess tissue is excised above the stapler before it is released. An additional important point is to make sure to add one or two sutures to reinforce the lower end of the side-to-side anastomosis, since there may be an open spot where the bowel was actually divided but not stapled over a short distance. Mesenteric defects must of course be closed just as in the suture technique. This results in a functional, end-to-end anastomosis, which is reliable and rapidly performed. The only disadvantage is the extra cost involved in using the stapling instruments. Depending on the clinical situation, however, the time saved may well be worth the extra cost.

INJURIES TO THE COLON.

Injuries to the colon can occur during gynecologic procedures, particularly in those involving left adnexal masses or in patients with previous inflammatory disease due to diverticulitis or previous pelvic inflammatory disease with adhesions involving the sigmoid or right colon. Rarely, the transverse colon can be so redundant as to be adherent to structures in the pelvis. When one is anticipating a possible resection of the colon, such as for ovarian malignancy, a bowel preparation is in order, such as the method previously described using neomycin and erythromycin base (or metronidazole). This combination has been shown to be effective against both gram-negative aerobic and anaerobic fecal organisms. Many surgeons add a parenteral intravenous antibiotic, given just before the operation.

Injury or perforation of the prepared colon can be primarily repaired using suture techniques similar to those used in small bowel repair. Small tears can be repaired with a few interrupted sutures in either one or two layers, but formal resection with anastomosis is required if a segment of colon must be resected along with the neoplasm. This can be done in nearly the same manner as in small bowel resection, by taking a small wedge of mesentery, taking care to preserve blood supply to the two ends, since this is especially critical for colonic surgery. As in the small bowel anastomosis, a two-layer closure using an inner layer of running absorbable suture material and an outer layer of interrupted nonabsorbable Lembert sutures of 4-0 strength, is an accepted method. It is important not to greatly narrow such an anastomosis and to be sure that the bowel ends are viable and have an adequate blood supply. If an adequate length of colon is available at both ends, the stapling technique described for the small bowel anastomosis can also be used.

Injury to the colon that has not been prepared in any way preoperatively presents a special problem; the extent of injury and the speed with which it is recognized and repaired are the key factors in deciding whether or not some type of colostomy is required. A minor injury to the colon (i.e., one that encompasses approximately 1 cm or less) or an injury with minimal fecal spillage that is recognized early can be treated by primary single- or double-layer closure. Nonabsorbable interrupted sutures should be used for the outer layer. Parenteral antibiotic therapy using a combination of drugs effective against both anaerobic and aerobic organisms should be started and maintained for several days postoperatively.

A major injury with extensive fecal spillage is another matter. Generally, a simple repair of such a lesion can be expected to fail, with resultant fecal peritonitis. The only exception to this is if the injury is to the cecum or ascending colon, where the stool is often liquid, and a primary closure may be feasible. If possible, the injured area should be exteriorized as a colostomy. If the area is below the level that can be easily exteriorized, however, there are at least two other options, depending on the extent of injury. Primary repair of the injured colon can be performed along with a proximal colostomy, such as a sigmoid or transverse colostomy (Fig. 5); the area should be drained with a sump drain. An alternative is resection with an end colostomy and a Hartmann procedure (closure of the rectal stump). Consultation with a general surgeon may be helpful in choosing the best approach.

In addition to injuries that occur in the course of vaginal or abdominal hysterectomy, oophorectomy, and other resective abdominal procedures, injuries can result from perforation of the uterus (e.g., in conjunction with dilatation and curettage, colpocentesis, or a laparoscopic or hysteroscopic procedure). Under these conditions, injury to the small bowel may not be directly observed, and it is necessary to watch for the development of signs of peritoneal irritation that may indicate either hemorrhage or actual perforation of viscera: If perforations are found at laparotomy, management depends on the nature of the injury, the presence of infection, and the duration of time from the occurrence of the injury to the time the patient is actually explored.

One can expect the broad range of complications that occur in general surgical patients to occur in the gynecologic surgical patient. Even in the absence of intestinal injury, certain intestinal complications can occur in gynecologic patients, specifically including paralytic ileus, small bowel obstruction, and obstruction of the colon. If not properly treated or recognized, obstruction can lead to infarction with very serious consequences.

Paralytic Ileus and Obstruction

Paralytic ileus can occur following laparotomy for any reason, and the manifestations are usually quite clear. Normally, following hysterectomy or laparotomy for any reason other than an intestinal procedure, there is a variable period of ileus in which the peristaltic activity is reduced or interrupted, and then the bowel resumes its normal activity. This ileus is usually associated with a great diminution of secretory activity such as pancreatic or biliary secretion. The lesser the procedure (e.g., oophorectomy alone), the more rapidly peristaltic activity resumes, and often there is no significant period of ileus at all. In certain patients, however, for reasons that are not always obvious but usually correlate with the magnitude of the trauma of the surgical procedure, peristaltic activity may be slow to return. These patients are intolerant to food and experience nausea and vomiting, or if they have not already been fed, may manifest abdominal distention with hypoactive bowel sounds. In addition, sometimes patients experience gas pains, which may be an early manifestation of partial small bowel obstruction or may be related to ileus involving the colon. The surgeon should be aware of this complication and be prepared to treat it when necessary. As a general rule, it is prudent to delay feeding patients until there is evidence of return of peristaltic activity. Either auscultatory evidence of bowel activity or a clear-cut documentation by the patient or nurse of passage of flatus is a good sign of peristaltic activity and indicates that feeding may be begun. To prevent more serious complications, it is prudent to start with liquids first. If the patient has problems with intolerance of liquids, and if nausea, vomiting, or cramps develop, feeding can be discontinued and the patient can be maintained on intravenous fluids. The decision to place such a patient on nasogastric suction depends on several considerations. If the patient is vomiting substantial amounts, and if there is significant abdominal distention, nasogastric suction is mandatory. Treatment solely with antiemetics is not a good practice, because nausea and vomiting may be based on intolerance of the patient's secretions, and primary treatment (i.e., removal of as much of these secretions possible) should be undertaken rather than symptomatic treatment alone. This is by no means an indictment of antiemetics, since nausea and vomiting frequently are simply a consequence of the patient's reaction to an anesthetic rather than paralytic ileus or bowel obstruction. With significant nausea, vomiting, or abdominal distention, x-rays of the abdomen should be obtained. Significant dilatation of the small bowel or colonic distention with gas in a patient with little or no abdominal tenderness is generally confirmatory evidence of an ileus rather than obstruction: In a specific situation, however, this distinction may be very difficult to make.

On the other hand, if ileus persists for a period longer than several days after an operation, bowel obstruction must be considered as an explanation, although an inflammatory process such as abscess or phlegmon may have developed, which can also account for this problem. If the patient has minimal abdominal distention and mild cramps and is passing flatus, she can usually be treated satisfactorily with fasting and intravenous fluids. Paralytic ileus that persists for more than 2 or 3 days in the patient with a soft abdomen who is slowly improving without any sign of peritoneal irritation generally can be expected to resolve completely. A combination of fasting and nasogastric suction, when indicated, is generally sufficient over several days to restore normal peristaltic activity. In these patients it is prudent to wait until the abdomen has become totally scaphoid and passage of flatus has occurred before attempting oral feedings.

The patient who is not doing well and who gradually becomes either progressively more distended—on the basis of clinical examination or radiograph—or who has substantial dilatation of the small bowel with fluid or gas, should be observed closely. This patient may develop a bowel obstruction. Unfortunately, such patients thought to have an ileus have, on occasion, been observed for too long, necessitating bowel resection when they were finally re-explored. Identification of small bowel obstruction can be difficult in the postoperative patient since many patients undergo a period of ileus. The patient who does not recover normally and continues to have dilated small bowel and a distended abdomen with crampy abdominal pain after 1 or 2 days of nasogastric suction, should be suspected of having a bowel obstruction rather than simple paralytic ileus. In postoperative follow-up of these patients, consultation with a general surgeon should be obtained in the event that re-exploration is indicated. There are certain indications for intestinal intubation using a Cantor tube or Miller—Abbott tube, but usually these tubes take some time to travel into the small intestine. Generally, it is preferable to start with a nasogastric tube. When there is abdominal distention and nasogastric suction produces little gastric return, however, a long intestinal tube should be considered. The patient should be observed closely. If peritoneal signs or fever develops, or the white blood count rises ominously, one should not defer re-exploration or general surgical consultation. If an abscess is suspected, a CT scan of the abdomen may be useful.

Colonic Obstruction

Occasionally, obstruction may be due to a colonic lesion. For example, in the course of hysterectomy, especially in the patient with an inflamed sigmoid colon (e.g., the patient who has had diverticulitis), adhesions in and around the sigmoid may result in a partial obstruction that manifests itself postoperatively by continued distention or by difficulty with, or inability to have, bowel movements. Such a patient should be treated conservatively, unless distention persists over a long period of time, in which case surgical intervention following diagnostic studies may be appropriate. If colonic obstruction is suspected on the basis of radiographic dilatation of the colon, flexible sigmoidoscopy and barium enema as initial steps are appropriate, and if there is convincing evidence of high-grade obstruction, the patient should be re-explored.

Appendectomy

Appendectomy performed incidental to gynecologic operations may be appropriate. Details of surgical technique are outlined in Figure 6. Clamping and dividing the mesoappendix after grasping the appendix with a Babcock clamp is a usual first step. The appendiceal stump is cleared of any residual mesoappendix, double clamped, and tied where crushed with a suture, such as 2-0 chromic catgut. The appendix is then amputated. Sterilizing the stump is an archaic procedure that has little, if any, proven benefit. Appendiceal stump inversion can be performed using a purse-string method or interrupted Lembert sutures. An alternative method of closing the appendix involves a stapling technique, which places a double row of staples at the appendiceal base. The appendix is then divided above the staple line. With the advent of laparoscopic approaches to a number of surgical problems (e.g., laparoscopic cholecystectomy), appendectomy has been added to the list of procedures that can be performed through the laparoscope.

Transverse Colostomy

In the event of a colonic obstruction or injury at the time of surgery, transverse colostomy occasionally is indicated. A small segment of transverse colon is freed of omentum and mesentery, and at the midpoint of the incision the fascial layers are sutured together beneath the colon through the mesenteric defect. This produces a solid support for the colonic loop, greatly reducing the possibility of accidental return of the colostomy into the peritoneal cavity. The technique is illustrated in Figure 5. A rubber catheter sutured in ring fashion is preferable to a rod, because it permits easy application of a colostomy appliance. The colostomy can be opened in the patient's room with one of the small portable cautery units now available. An alternative technique, which is equally effective, is simply to bring the transverse loop through a small transverse incision and fix the colon to the subcutaneous tissue with interrupted sutures. The colostomy is matured in the same way, in delayed fashion.

Repair of Wound Dehiscence

Major wound dehiscence with evisceration is fortunately a rare event. Proper management consists of early diagnosis and prompt treatment. There are numerous causes of dehiscence, but generally they fall into three broad categories: (1) a major necrotizing wound infection is responsible; (2) there is a mechanical problem, such as inadequate wound closure or defective suture material; (3) tissue quality is poor, such as in a debilitated patient. Whatever the cause, the fascia and muscle layers must be closed. A repair that is very effective, especially in the patient with a wound infection, is illustrated in Figure 7. Posterior and anterior fascia are sutured together, excluding skin, subcutaneous tissue, and peritoneum, using a suture such as No. 1 or No. 2 nylon. This results in a solid closure, and it avoids closing the skin in a patient with an infected wound. In addition, these sutures need not be removed, in contrast to the through-and-through retentions, which include skin.

Differential Diagnosis of the Acute Abdomen

The gynecologist and general surgeon frequently consult each other about patients who present with acute abdominal pain involving the lower abdomen. Conditions such as diverticulitis of the sigmoid colon may mimic pelvic inflammatory disease or a ruptured ovarian cyst, but bowel symptoms, including diarrhea, obstipation, and extension of pain into the left lower abdomen outside the pelvis point to diverticulitis. In addition, diverticulitis usually occurs in an older age group than the gynecologic conditions it can mimic. In addition to the clinical assessment, CT of the abdomen may be useful in helping arrive at a precise diagnosis.

Appendicitis can be a difficult diagnosis in the young, sexually active female. The conditions that can mimic this disease are well known and need not be elaborated here. If there is doubt regarding the diagnosis, the patient should be hospitalized and serial observations and repeated leukocyte counts should be performed. An emergency barium enema, pelvic ultrasound, and CT of the abdomen can be very useful in establishing a diagnosis. The patient who presents with abdominal pain localizing to the right lower quadrant of the abdomen in conjunction with nausea and vomiting, and who has a relatively normal pelvic exam, moderate fever, and leukocytosis, most likely has appendicitis. In difficult situations, however, close consultation between a gynecologist and general surgeon may be very useful in establishing a likely diagnosis and avoiding operation in reversible gynecologic problems. On the other hand, the availability of new techniques using the laparoscope may allow a more liberal policy for exploration, and pathology, as encountered, can be dealt with when appropriate through the laparoscope.