Iatrogenic Internal Hernia as a Cause of Small Bowel Ischemia During Pregnancy

Introduction

An internal hernia is a protrusion of abdominal viscera through an intra-abdominal opening with the herniated viscera remaining inside the abdominal cavity. Internal hernias are rare in general, including during pregnancy. Postoperative adhesions are the most common cause of intestinal obstruction during pregnancy. Recent case reports suggest that gastric bypass surgery may increase the risk of internal hernia in pregnant women. ¹ Internal hernias subsequent to surgical procedures in pregnant women are not well documented. Awareness of these hernias is particularly important because of the challenge of their diagnosis and the potential maternal and fetal risks. A case of iatrogenic herniation and necrosis of 1.5 m of the small intestine, through a defect in the mesointestine at 28 weeks' gestation, occurring 18 years after a jejunostomy, is reported.

Case

A 39-year-old woman (gravida 3, para 0), was referred to the Western Galilee Hospital at 28 weeks' gestation for diffuse abdominal pain and vomiting, without other gastrointestinal or general complaints. Her past medical history was positive for chronic hypertension, type 2 diabetes mellitus, and cholecystolithiasis. At age 21, she had been hospitalized in the intensive care unit after almost drowning. A prolonged artificial ventilation was complicated by a tracheo-esophageal fistula above the carina with a constriction of the trachea to a 5-mm diameter at the level of rings 2–3. Surgical repair of the tracheal constriction was in two stages: first, a gastrostomy, jejunostomy, and dilatation of the constricted trachea; followed by closure of the fistula and resection of the constricted tracheal rings.

The initial physical examination at the present admission, 18 years after the jejunostomy, revealed a bloated abdomen with diffuse abdominal tenderness. Maximal tenderness was at the epigastric region. Auscultation was normal, with no hyper- or hypoactive bowel sounds. Body temperature per os was 36.8°C, blood pressure was 143/90, regular heart rate was 90 beats per minute, hemoglobin was 13.4 g/dL, and white blood cell count (WBC) was 7900 with no immature neutrophils. Electrolytes, liver and renal functions, amylase, and coagulation profile were all normal.

Obstetric ultrasound examination revealed a normal appropriate for gestational age fetus with regular fetal heart rate, normal fetal movments, and a normal amount of amniotic fluid. On digital vaginal examination the patient's cervix was found to be posterior, closed, and 40% effaced; and with intact membranes, normal discharge, and no bleeding. No uterine activity was recorded. Intramuscular betamethasone (12-mg injection) was given to stimulate fetal lung maturation.

A “one shot” supine/flat abdominal plain radiograph showed the fetus in a vertex presentation and dilated loops of bowel without free air in the abdomen (Fig. 1). Abdominal ultrasonography showed dilated small bowel loops with thickening of the bowel wall to 7 mm and free fluid in a moderate amount (Fig. 2).

OPEN IN VIEWER

FIG. 1.

A “one shot” supine abdominal plain radiograph shows the fetus in a vertex presentation, and dilated loops of bowel without free air in the abdomen. The gas pattern was influenced most probably by the enlarged uterus.

OPEN IN VIEWER

FIG. 2.

Abdominal ultrasound of dilated small bowel loops with thickening of the bowel wall to 7 mm and free fluid in moderate amount.

At this stage, amniocentesis to rule out amniotic infection and a computed tomography scan were considered but not performed because the patient's condition deteriorated and there was indication of an intra-abdominal process. A nasogastric tube was inserted, antibiotic treatment initiated, and an exploratory laparotomy performed.

Laparotomy revealed a large amount of bloody, turbid fluid, and a left upper abdominal internal hernia with an incarcerated 1.5 m necrotic distal small bowel. The necrotic bowel segment was resected en bloc and a side-to-side primary ileal anastomosis using an endo-gastrointestinal stapler was performed. The hernial orifice at the mesointestine was sutured to prevent recurrence of bowel herniation. An estimated 3 m of normal bowel were left, with an intact ileocecal valve. No uterine activity was detected prior to surgery or the day following. Daily nonstress testing and biophysical profile were normal before and after surgery. The postoperative course was normal for 2 days, but on the third postoperative day, at 28 + 6 weeks' gestation, an urgent cesarean section was performed because of the onset of heavy vaginal bleeding subsequent to placental separation. The premature newborn weighed 1417 g; the Apgar score was 9/9. Antibiotic treatment was continued for 3 days postoperatively. The patient was discharged 6 days postsurgery. At age 19 months, the infant is developing well.

Discussion

Internal hernia as a cause of intestinal obstruction is rare, accounting for 0.2%–-0.9% of autopsy cases. ² Its rate during pregnancy is unknown. In an earlier case report of idiopathic internal hernia during pregnancy, ³ the authors delineated diagnostic challenges and risk factors of this condition.

Increased prevalance of pelvic inflammatory disease, and more recently, increased performance of gastric bypass surgery, ¹ have been proposed as explanations for the rising incidence of small-bowel obstruction. The risk of obstruction during pregnancy is particularly crucial at three develpmental stages: first, between 16 and 20 gestational weeks when the uterus is growing out of the pelvis to the abdominal cavity; second, near term, when the fetal head begins to descend; and finally, immediately after delivery, when the uterus contracts vigorously. ⁴ The time lag between abdominal or pelvic surgery and pregnancy, and not a woman's age or parity, has been identified an important risk factor of abdominal obstruction during pregnancy. ⁴

There are no specific signs or symptoms of internal hernia. Although partial obstruction does not necessitate immediate surgery, clinical suspicion of bowel obstruction should prompt the taking of an abdominal radiograph. Nevertheless, the latter does not usually reveal the cause. During early obstruction, and even in the presence of a strangulated bowel, a plain abdominal radiograph can be normal. In the present case, a plain supine abdominal radiograph raised suspicion of a small bowel obstruction and prompted surgical treatment. A “one shot” supine/flat abdominal radiograph is considered superior by the current authors to an upright abdominal radiograph in pregnant woman because the supine/flat abdominal radiograph is clearer and more physiologic details are viewable. Ultrasonography can also help diagnosis by demonstrating dilated bowel loops, thickened bowel wall, and free fluid inside the abdominal cavity. Unclear diagnosis is an indication for performing CT. Although CT evaluation, if accurate and reliable, may play an important role in the diagnosis of internal hernia, its documentation in the literature for this cause is scarce. ⁵ Iodine-based contrast material should be avoided if possible.

Amniotic fluid infection is unlikely in the presence of a 10/10 fetal biophyscal profile, such as in the present case. In addition, during diagnostic amniocentesis, possible passage of the needle through the infected abdomen risks inserting bacteria into the amniotic cavity. The evidence is in favor of injecting betamethasone corticosteroids to stimulate fetal lung maturation between 24 and 34 weeks' gestation, as abdominal surgery might result in pre-term delivery. ⁶

Once complete bowel obstruction is diagnosed, conservative treatment is inappropriate. Early laparotomy is crucial because of the high risks of maternal and fetal morbidity and mortality in the case of delayed surgery. ⁷ Prophylactic tocolytic treatment before, during, and after surgery, if an intraamniotic infection or placental separation is not suspected, is generally preferred by the current authors. ⁸

In the late third trimester, a cesarean section may be performed at the time of the exploration, depending upon the clinical and obstetrical indications. Although the possiblity exists that the exploration may reveal negative results the risks of laparotomy or preterm labor, compared to the risk of maternal and fetal morbidity and mortality in cases of neglected intestinal obstruction, usually justify the exploration. ⁹

Conclusions

In conclusion, clinical signs of intestinal obstruction, in the absence of an inflammatory intra-abdominal process or an external hernia, should raise suspicion of an internal hernia, when patient history reveals a previous abdominal operation. In the current case, the abdominal surgery had been performed 18 years earlier. Diagnosis of internal hernia complicated by intestinal obstruction during pregnancy should prompt an urgent explorative laparotomy because of the potential effect of delayed treatment on fetal and maternal morbidity and mortality.