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Mesenteric defects as a cause of intestinal volvulus without malrotation and as the possible primary etiology of intestinal atresia
Mesenteric Defects as a Cause of Intestinal Without Malrotation and as the Possible Etiology of Intestinal Atresia
Volvulus Primary
By Preston R. Black, Dale Mueller, John Crow, Robert C. Morris, and Aliya N. Husain Maywood, Illinois 0 Mesenteric defects can lead to intestinal volvulus even when the midgut is normally rotated. There are two types of mesenteric defects: basilar, in which the entire base of the mesentery is involved, and segmental, in which only an isolated portion of the mesentery is affected. These defects can present at any age, and the clinical symptoms depend on the extent of the disease and the amount of intestine involved in the volvulus. In the newborn, the basilar defects have clinical signs and symptoms similar to those of midgut volvulus secondary to malrotation. Similar to midgut volvulus secondary to malrotation, this is a surgical emergency. In older patients, basilar defects can be misdiagnosed because of the normal placement of the ligament of Treitz and because of failure to consider mesenteric defects as a possible cause. The treatment for basilar mesenteric defects is intestinal fixation. Intestinal volvulus secondary to segmental defects always presents as intestinal obstruction. In the newborn, these lesions may be indistinguishable from intestinal atresia. Older children present with intestinal obstruction of an unknown cause. Resection of the affected intestine is the treatment for segmental mesenteric defects. Intestinal mesenteric abnormalities as a cause of intestinal atresia unifies under one etiology all the lesions observed in intestinal atresia. Although this theory does not rule out other causes of intestinal atresia, intestinal mesenteric defects may be the primary condition under which intestinal atresia occurs. Copyright o 1994 by W.B. Saunders Company INDEX WORDS: Mesenteric defects; volvulus; intestinal atresia.
M
IDGUT VOLVULUS in association with intestinal malrotation is a well-recognized disease in children, with many reports in the literature. However, intestinal volvulus without anomalies of rotation and fixation is rare in children. There are few reports in the literature on this condition, and little is offered about the possible etiology. Herein we report on six patients with intestinal volvulus without concurrent malrotation. A review of these patients provides some insight into this disease. Insight into the etiology of intestinal atresia also is obtained. CASE REPORTS Case I A 6-week-old black female presented to another hospital with a 2-day history of vomiting and a l-day history of irritability and lethargy. Before presentation she had been eating and growing normally. While being evaluated at that hospital, abdominal distension was noted, and acute apnea and bradycardia developed. The patient was transferred to our hospital, at which time she was ~~fouma/ofPediarricSurgery.
Vol29,
No 10 (October),
1994: pp 1339-1343
afebrile and had normal vital signs. Upon examination, she had signs of severe dehydration. Her abdomen was distended and mildly tender. There were no bowel sounds, and no distinct masses were palpable. Plain films of the abdomen showed a central abdominal mass that displaced the intestines superiorly and laterally. A computerized axial tomography scan of the abdomen showed that the mass consisted of multiple fluid-filled loops of bowel. The patient was rehydrated and taken to the operating room for an exploratory laparotomy. During the operation, an isolated midjejunal volvulus with a large mass of necrotic bowel was discovered. There was no malrotation because the ligament of Treitz and the cecum were in the normal position. The volvulus was centered on an abnormal segment of mesentery that was foreshortened and attenuated. The affected bowel was resected, and a jejunostomy and mucus fistula were created. Postoperatively, the patient did well. She was maintained on hyperahmentation. Four weeks after the initial operation, the jejunostomy was taken down, and intestinal continuity was reestablished. After this operation, the patient returned to a normal diet and was discharged from the hospital. Two and one-half years later, the patient was on a normal diet and her growth was normal.
Case
2
This 2,860 g boy was the older of twins born at 36 weeks’ gestation, delivered by cesarean section. The postpartum period was uneventful except for mild duskiness, with oxygen saturation decreasing to 90% when feeding was begun. This resolved within 24 hours. The child did well until 3 days of age, when he had the sudden onset of abdominal distension and bilious vomiting. A flat plate of the abdomen showed a normal gas pattern and no signs of masses orobstruction. An upper gastrointestinal series with a small bowel follow-through showed no evidence of malrotation or midgut volvulus. However, 2 hours into the study, no barium had passed beyond the mid small intestine, and none had entered the colon. This was believed to be consistent with small bowel obstruction, and the patient was taken to the operating room. During an exploratory laparotomy, distal ileal volvulus was noted, secondary to a foreshortened mesentery (Fig 1). All the intestine within the volvulus was viable. At the base of the volvulus was a small perforation that was localized. The entire area was resected, and an end-to-end anastomosis was performed. The postoperative course was uneventful, and oral alimentation was begun. He was soon tolerating a normal diet and gaining weight.
From the Division of Pediatric Surgery, Department of Swge~, and the Department of Pathology, &itch School of Medicine, Loyola Universiry Chicago, Maywood, IL. Date accepted: August 24, 1993. Address reprint requests to Preston R. Black, MD, Department of Surgey, Stritch School of Medicine, Loyola University Chicago, Maywood, IL 60153. Copyright o 1994 by W.B. Saunders Company 0022-346819412910-0012$03.OOjO 1339
BLACK ET AL
thereafter. Eighteen months after surgery, he has a normal diet, with no evidence of malabsorption. He is growing normally.
Case 4 A 4-day-old boy was seen because of abdominal distension, melanotic stools, and bilious vomiting. He was born at 40 weeks’ gestation, the product of an uncomplicated pregnancy. In the newborn nursery, it was noted that he was jittery. He was found to by hypoglycemic, which was treated by early feedings. Oral treatment of the hypoglycemia was unsuccessful because of vomiting. Intravenous therapy corrected the hypoglycemia. Because the jitteriness continued and because of other symptoms, a cranial computed tomography scan was obtained. This showed grade III intraventricular hemorrhage. The patient was transferred to our hospital, where a neurological workup was undertaken. On the fourth day of life, the patient’s abdomen became acutely distended, and there were increasing amounts of bilious drainage from his nasogastric tube. He also had an elevated leukocyte count, with a left shift and thrombocytopenia. Plain tilms of the abdomen showed dilated loops of bowel with air-fluid levels. The patient was taken to the operating room for an exploratory laparotomy. During the operation, all the small intestine (except for the proximal 2 cm of jejunum and the distal 1 cm of ileum) was found to be completely gangrenous. The cause of this proved to be a volvulus of the intestine around the base of its mesentery. The length of the mesenteric root, around which the volvulus had occurred, appeared shorter than normal. The ligament of Treitz was in its normal positions, as was the cecum. None of the colon was involved in the twisting of the bowel. The nonviable bowel was resected, and a primary anastamosis was constructed. The patient died 12 hours after surgery.
Case 5
Fig 1. lntraoperative photograph shows a segmental mesenteric defect. Note the single blood vessel traversing the middle portion of the abnormal mesentery (bottom arrow). The volvulus has caused necrosis and disruption of a small segment of the intestine (top arrow).
He was discharged home 8 days after the operation. Two years later he continues to thrive.
Case 3 A 2,170 g boy was born at 34 weeks’ gestation. A prenatal ultrasound examination had shown dilated loops of intestine that had thickened walls and were aperistaltic. Abdominal x-rays shortly after birth showed dilated loops of proximal bowel, with no air distally. There was no free air or other sign of perforation. These findings were believed to be consistent with intestinal atresia, and the patient was taken to the operating room. During exploration, dilated loops of small intestine were noted. One large loop of intestine appeared gangrenous and was adherent to the anterior abdominal wall. The small intestine was mobilized, and the entire complex was found to be a part of a jejunoilial volvulus secondary to a foreshortened mesentery. The remainder of the bowel was normal in appearance, with normal fixation. The affected intestine was resected, and a primary anastamosis was performed. The patient’s postoperative course was complicated by an adhesive bowel obstruction that required lysis of adhesion. Oral feeding was begun, and an age-appropriate diet followed shortly
A 12-year-old girl presented with a 3-day history of abdominal distension and vomiting. She had been born at 28 weeks’ gestation and suffered grade IV intracranial hemorrhage. Subsequently, hydrocephalus developed, which required placement of an intraventricular shunt. The patient was developmentally delayed and was diagnosed as being mentally retarded and having cerebral palsy. Over the next several years, the patient had many problems with her intraventricular shunt, necessitating multiple revisions. Her first episode of intestinal obstruction occurred when she was 10 years old. She was taken to the operating room for an exploratory laparotomy. At that time, she had what appeared to be an adhesive intestinal obstruction, but there was some twisting of the bowel. Because the ligament of Treitz and the cecum were in their normal anatomic positions, it was believed that the volvulus was the result of the adhesions. Postoperatively, she did well but returned to the hospital within 9 months for operative relief of another intestinal obstruction. Again it appeared that the obstruction was secondary to adhesions. Twisting of the bowel was noted. This also was believed to be related to an adhesive band, and the twisting was not primary in causing the obstruction. One year later, the patient returned with a 2-day history of abdominal distension, vomiting, and irritability. She was taken to the operating room for exploratory surgery, which showed that the obstruction was secondary to a volvulus including the intestine, from the ligament of Treitz to the ileocecal valve. Careful inspection showed that there was no evidence of malrotation. However, the base of the small bowel mesentery was very narrow, which allowed twisting to occur (Fig 2). To prevent further episodes of volvulus, the jejunum was pexed to the colon in the left upper quadrant, and the distal ileum was pexed to the ascending colon.
INTESTINAL VOLVULUS FROM MESENTERIC DEFECTS
Fig 2. lntraoperative photograph of case 5. Note the abnormally shortened mesentery at the base of the small intestine. The mesentery between the arrows represents the entire mesenteric root.
Postoperatively, the patient’s intestinal function recovered, and a normal diet was begun. Six months after surgery, the patient’s diet is normal, and she has had no further symptoms.
Case 6 A 3-day-old boy had been noted to have a hypoechoic bowel pattern on prenatal ultrasound. After delivery, the results of the physical examination were normal, with no abdominal distension, pain, or masses. A barium enema showed a meconium plug extending from the rectosigmoid colon to the proximal transverse colon. There was reflux into the terminal ileum, but no intestinal abnormalities. Because of poor feeding, an upper gastrointestinal series was performed, which showed poor gastric emptying with extrinsic compression of the gastric antrum. The extrinsic compression was believed to be secondary to air-filled loops of bowel. The distension worsened, and mild abdominal pain developed. A computed tomography scan of the abdomen showed multiple loops of dilated intestine, believed to be consistent with distal ileal obstruction. At operation there was distal ileal obstruction secondary to intestinal atresia. However. the cause of the atresia was clearly a segmental mesenteric defect in which a volvulus had occurred. The atresia was in continuity, and the abnormal segment of intestine was viable but separated from the remainder of the ileum. The abnormal segment and the atresia were excised, and a primary anastamosis was performed. Shortly after surgery, a normal diet was begun, and the patient was discharged 1 week after surgery. Six months later, he is tolerating a diet appropriate for his age and is growing normally.
DISCUSSION
Intestinal volvulus is a surgical emergency that requires rapid diagnosis and prompt treatment to reduce morbidity and mortality. Recognition of intestinal volvulus before intestinal infarction is the hallmark for minimizing morbidity and mortality. In the pediatric population, intestinal volvulus is most commonly associated with disorders of rotation and fixation.lm4The keys to expeditious diagnosis of malrotation and early surgical intervention are a high index of suspicion and swift radiographic evaluation including appropriate contrast studies. The radiographic
1341
findings in malrotation are well described5-7 and in most cases are easy to recognize. Intestinal volvulus without malrotation is uncommon and is not as easily recognizable as volvulus with malrotation. Thus, the former is associated with a high mortality rate.8 The high complication rate is primarily the result of deIays in diagnosis. The delays are secondary to the diversity of presentations of intestinal volvulus without disorders of malrotation and lack of specific clinical or radiographic features. Furthermore, a wide variety of mesenteric defects can occur during fetal development. These range from lesions involving a short, clearly defined area of the small intestine (segmental defects) to lesions involving the entire base of the mesentery (basilar defects). In his classic study, Dott9 divided intestinal rotation into three stages. During the first stage, the rapidly elongating midgut forms an S-shaped flexure before it begins its return to the abdominal cavity. In the second stage, the intestine returns to the abdominal cavity, completing a 270” counterclockwise turn as it does so. This stage is the most important in the final configuration of the intestines within the peritoneal cavity. During the third stage, little rotation occurs. However, it is during this stage that the mesentery fuses with the posterior abdominal wall, along the line of the superior mesenteric artery. This is a very critical stage in intestinal development, allowing the small intestine, which was originally based on a very narrow pedicle at the origin of the superior mesenteric artery, to develop a wide secondary attachment along the root of the mesentery. This last step in intestinal rotation is key to providing the extensive attachments that make volvulus impossible (Fig 3). Failure of fusion during the third stage of intestinal fixation is the most likely cause when the entire base of the mesentery is involved in the process (Fig 4). There have been other reports of this type of lesion.‘O-I2 However, the etiology of segmental mesenteric defects is not clear. Little has been written about the development of the mesentery, except for the ventral mesentery, which gives rise to the lesser omentum, the falciform ligament, and the visceral peritoneum of the liver. Persistence of the ventral mesentery has been reported, but no other isolated mesenteric defects are present in the literature.13 In this present study, two patients had defects that involved the entire base of the mesentery. The remainder had segmental defects. The etiology of segmental mesenteric defects is unclear. It appears that each of these defects resulted from either excess growth of a small segment of small intestine or the uncontrolled growth
1342
Fig 3. illustration of the normal, broad-based mesenteric root. It is clear that the broader the base, the more difficult it is for volvulus to occur.
of an isolated segment of mesentery. Either mechanism would have resulted in a portion of intestine having a small segment of mesentery with a narrow base. The small base would allow free movement and twisting of that segment of the intestine (Fig 5). The clinical presentation of these defects depends on the extent of the defect and the age of presentation. All the children with segmental mesenteric defects had signs of obstruction at the time of presentation. In the neonatal period, this defect was
Fig 4. Illustration of an abnormally short mesenteric root. Twisting around such a short base is more probable than a base twisting around of normel length.
BLACK ET AL
misdiagnosed most often as intestinal atresia. The older children were taken to the operating room with intestinal obstruction of an unknown cause. The neonates with basilar mesenteric defects had a clinical presentation indistinguishable from midgut volvulus secondary to intestinal malrotation. The older child in our series with a basilar mesenteric defect posed somewhat of a diagnostic dilemma. She presented with intestinal obstruction on two occasions. Both times the obstruction was believed to be secondary to adhesions even though twisting of the bowel was noted during both operations. In each instance, a normally placed ligament of Treitz lead the surgeon to believing that volvulus was not the reason for the obstruction. Treatment should be individualized. Patients with basilar disease require fixation of the intestine to prevent subsequent twisting. Because the intestine has undergone normal rotation, there are no Ladd bands, and the appendix is in its normal location. Segmental mesenteric defects require resection of the affected bowel. The decision to perform a primary or delayed anastamosis is made at the time of surgery. Since the classic studies of Louw and Barnard,14 interuterine mesenteric vascular catastrophe has been recognized as the cause of intestinal atresia. In 1959, Courtoisrs further demonstrated that if an intestinal loop is isolated and its blood supply is poor, the loop would be reabsorbed. The pathology encountered in our sixth case suggests that segmental mesenteric defects may be the major cause of intestinal atresia. Because these defects appear to be highly prone to twisting and if intrauterine volvulus of intestine occurs (thus compromising the blood supply), intestinal atresia can result. Furthermore, if several segmental defects with volvulus were to occur throughout the small intestine, then multiple atresias would result.
1343
INTESTINAL VOLVULUS FROM MESENTERIC DEFECTS
The so-called apple core lesion seen in cases of intestinal atresia may be caused by basilar defects, with more extensive intestinal necrosis than that seen with segmental defects. Consideration of mesenteric defects as the major cause of intestinal atresia would
allow all the various lesions observed to be unified under one consistent etiology. Moreover, because colonic mesenteric defects have never been described either antenatally or postnatally, this theory also would explain the rareness of colonic atresia.
REFERENCES 1. Snyder WH, Chaffin L: Embryology and pathology of the intestinal tract: Presentation of 40 cases of malrotation. Ann Surg 140:368-380,1954 2. Stewart DR, Colodny AL, Daggett WC: Malrotation of the bowel in infants and children: A 15year review. Surgery 79:716720,1976 3. Andrassy RJ, Mahour GH: Malrotation of the midgut in infants and children: A 25year experience. Arch Surg 116:158-160, 1981 4. Rescorla FJ, Shedd FJ, Grosfeld JL, et al: Anomalies of intestinal rotation in childhood: Analysis of 447 cases. Surgery 108:710-716,199O 5. Houston CS, Wittenborg MH: Roentgen evaluation of anomalies of rotation and fixation of the bowel in children. Radiology 84:1-18,1965 6. Berdon WE, Baker DH, Bull S, et al: Midgut malrotation and volvulus: Which films are most helpful? Radiology 96:375-383,197O 7. Graines PA, Saunders AJS, Drake D: Midgut malrotation diagnosed by ultrasound. Clin Radio1 38:51-53,1987
8. Yadav K, Nayar PM, Pate1 RV, et al: Volvulus neonatorium without malrotation. J Indian Med Assoc 85:16-19,1987 9. Dott NM: Anomalies of intestinal rotation: Their embryology and surgical aspects, with report of five cases. Br J Surg 11:251-286, 1923 10. Cueto J, Mednoza CB Jr, Easley GW, et al: Volvulus of the entire small intestine without associated mahotation. Arch Surg 96:953-955,1968 11. Wilkinson TS, Stone HH: Intestinal volvulus without malrotation in a four month old infant. Am Surg 33:3665-3666, 1967 12. Usmani SS, Kenigsberg K: Intrauterine volvulus without malrotation. J Pediatr Surg 26:1409-1410,199l 13. Gray SW, Skandalakis JE: Embryology for Surgeons. Philadelphia, PA, Saunders, 1972 14. Louw JH, Barnard CN: Congenital intestinal atresia: Observations on its origin. Lancet 2:1065-1067,1955 15. Courtois R: Les origines foetales des occlusions congenitales grele dites par atresia. J Chir 78:405-409, 1959
Volvulus Primary
By Preston R. Black, Dale Mueller, John Crow, Robert C. Morris, and Aliya N. Husain Maywood, Illinois 0 Mesenteric defects can lead to intestinal volvulus even when the midgut is normally rotated. There are two types of mesenteric defects: basilar, in which the entire base of the mesentery is involved, and segmental, in which only an isolated portion of the mesentery is affected. These defects can present at any age, and the clinical symptoms depend on the extent of the disease and the amount of intestine involved in the volvulus. In the newborn, the basilar defects have clinical signs and symptoms similar to those of midgut volvulus secondary to malrotation. Similar to midgut volvulus secondary to malrotation, this is a surgical emergency. In older patients, basilar defects can be misdiagnosed because of the normal placement of the ligament of Treitz and because of failure to consider mesenteric defects as a possible cause. The treatment for basilar mesenteric defects is intestinal fixation. Intestinal volvulus secondary to segmental defects always presents as intestinal obstruction. In the newborn, these lesions may be indistinguishable from intestinal atresia. Older children present with intestinal obstruction of an unknown cause. Resection of the affected intestine is the treatment for segmental mesenteric defects. Intestinal mesenteric abnormalities as a cause of intestinal atresia unifies under one etiology all the lesions observed in intestinal atresia. Although this theory does not rule out other causes of intestinal atresia, intestinal mesenteric defects may be the primary condition under which intestinal atresia occurs. Copyright o 1994 by W.B. Saunders Company INDEX WORDS: Mesenteric defects; volvulus; intestinal atresia.
M
IDGUT VOLVULUS in association with intestinal malrotation is a well-recognized disease in children, with many reports in the literature. However, intestinal volvulus without anomalies of rotation and fixation is rare in children. There are few reports in the literature on this condition, and little is offered about the possible etiology. Herein we report on six patients with intestinal volvulus without concurrent malrotation. A review of these patients provides some insight into this disease. Insight into the etiology of intestinal atresia also is obtained. CASE REPORTS Case I A 6-week-old black female presented to another hospital with a 2-day history of vomiting and a l-day history of irritability and lethargy. Before presentation she had been eating and growing normally. While being evaluated at that hospital, abdominal distension was noted, and acute apnea and bradycardia developed. The patient was transferred to our hospital, at which time she was ~~fouma/ofPediarricSurgery.
Vol29,
No 10 (October),
1994: pp 1339-1343
afebrile and had normal vital signs. Upon examination, she had signs of severe dehydration. Her abdomen was distended and mildly tender. There were no bowel sounds, and no distinct masses were palpable. Plain films of the abdomen showed a central abdominal mass that displaced the intestines superiorly and laterally. A computerized axial tomography scan of the abdomen showed that the mass consisted of multiple fluid-filled loops of bowel. The patient was rehydrated and taken to the operating room for an exploratory laparotomy. During the operation, an isolated midjejunal volvulus with a large mass of necrotic bowel was discovered. There was no malrotation because the ligament of Treitz and the cecum were in the normal position. The volvulus was centered on an abnormal segment of mesentery that was foreshortened and attenuated. The affected bowel was resected, and a jejunostomy and mucus fistula were created. Postoperatively, the patient did well. She was maintained on hyperahmentation. Four weeks after the initial operation, the jejunostomy was taken down, and intestinal continuity was reestablished. After this operation, the patient returned to a normal diet and was discharged from the hospital. Two and one-half years later, the patient was on a normal diet and her growth was normal.
Case
2
This 2,860 g boy was the older of twins born at 36 weeks’ gestation, delivered by cesarean section. The postpartum period was uneventful except for mild duskiness, with oxygen saturation decreasing to 90% when feeding was begun. This resolved within 24 hours. The child did well until 3 days of age, when he had the sudden onset of abdominal distension and bilious vomiting. A flat plate of the abdomen showed a normal gas pattern and no signs of masses orobstruction. An upper gastrointestinal series with a small bowel follow-through showed no evidence of malrotation or midgut volvulus. However, 2 hours into the study, no barium had passed beyond the mid small intestine, and none had entered the colon. This was believed to be consistent with small bowel obstruction, and the patient was taken to the operating room. During an exploratory laparotomy, distal ileal volvulus was noted, secondary to a foreshortened mesentery (Fig 1). All the intestine within the volvulus was viable. At the base of the volvulus was a small perforation that was localized. The entire area was resected, and an end-to-end anastomosis was performed. The postoperative course was uneventful, and oral alimentation was begun. He was soon tolerating a normal diet and gaining weight.
From the Division of Pediatric Surgery, Department of Swge~, and the Department of Pathology, &itch School of Medicine, Loyola Universiry Chicago, Maywood, IL. Date accepted: August 24, 1993. Address reprint requests to Preston R. Black, MD, Department of Surgey, Stritch School of Medicine, Loyola University Chicago, Maywood, IL 60153. Copyright o 1994 by W.B. Saunders Company 0022-346819412910-0012$03.OOjO 1339
BLACK ET AL
thereafter. Eighteen months after surgery, he has a normal diet, with no evidence of malabsorption. He is growing normally.
Case 4 A 4-day-old boy was seen because of abdominal distension, melanotic stools, and bilious vomiting. He was born at 40 weeks’ gestation, the product of an uncomplicated pregnancy. In the newborn nursery, it was noted that he was jittery. He was found to by hypoglycemic, which was treated by early feedings. Oral treatment of the hypoglycemia was unsuccessful because of vomiting. Intravenous therapy corrected the hypoglycemia. Because the jitteriness continued and because of other symptoms, a cranial computed tomography scan was obtained. This showed grade III intraventricular hemorrhage. The patient was transferred to our hospital, where a neurological workup was undertaken. On the fourth day of life, the patient’s abdomen became acutely distended, and there were increasing amounts of bilious drainage from his nasogastric tube. He also had an elevated leukocyte count, with a left shift and thrombocytopenia. Plain tilms of the abdomen showed dilated loops of bowel with air-fluid levels. The patient was taken to the operating room for an exploratory laparotomy. During the operation, all the small intestine (except for the proximal 2 cm of jejunum and the distal 1 cm of ileum) was found to be completely gangrenous. The cause of this proved to be a volvulus of the intestine around the base of its mesentery. The length of the mesenteric root, around which the volvulus had occurred, appeared shorter than normal. The ligament of Treitz was in its normal positions, as was the cecum. None of the colon was involved in the twisting of the bowel. The nonviable bowel was resected, and a primary anastamosis was constructed. The patient died 12 hours after surgery.
Case 5
Fig 1. lntraoperative photograph shows a segmental mesenteric defect. Note the single blood vessel traversing the middle portion of the abnormal mesentery (bottom arrow). The volvulus has caused necrosis and disruption of a small segment of the intestine (top arrow).
He was discharged home 8 days after the operation. Two years later he continues to thrive.
Case 3 A 2,170 g boy was born at 34 weeks’ gestation. A prenatal ultrasound examination had shown dilated loops of intestine that had thickened walls and were aperistaltic. Abdominal x-rays shortly after birth showed dilated loops of proximal bowel, with no air distally. There was no free air or other sign of perforation. These findings were believed to be consistent with intestinal atresia, and the patient was taken to the operating room. During exploration, dilated loops of small intestine were noted. One large loop of intestine appeared gangrenous and was adherent to the anterior abdominal wall. The small intestine was mobilized, and the entire complex was found to be a part of a jejunoilial volvulus secondary to a foreshortened mesentery. The remainder of the bowel was normal in appearance, with normal fixation. The affected intestine was resected, and a primary anastamosis was performed. The patient’s postoperative course was complicated by an adhesive bowel obstruction that required lysis of adhesion. Oral feeding was begun, and an age-appropriate diet followed shortly
A 12-year-old girl presented with a 3-day history of abdominal distension and vomiting. She had been born at 28 weeks’ gestation and suffered grade IV intracranial hemorrhage. Subsequently, hydrocephalus developed, which required placement of an intraventricular shunt. The patient was developmentally delayed and was diagnosed as being mentally retarded and having cerebral palsy. Over the next several years, the patient had many problems with her intraventricular shunt, necessitating multiple revisions. Her first episode of intestinal obstruction occurred when she was 10 years old. She was taken to the operating room for an exploratory laparotomy. At that time, she had what appeared to be an adhesive intestinal obstruction, but there was some twisting of the bowel. Because the ligament of Treitz and the cecum were in their normal anatomic positions, it was believed that the volvulus was the result of the adhesions. Postoperatively, she did well but returned to the hospital within 9 months for operative relief of another intestinal obstruction. Again it appeared that the obstruction was secondary to adhesions. Twisting of the bowel was noted. This also was believed to be related to an adhesive band, and the twisting was not primary in causing the obstruction. One year later, the patient returned with a 2-day history of abdominal distension, vomiting, and irritability. She was taken to the operating room for exploratory surgery, which showed that the obstruction was secondary to a volvulus including the intestine, from the ligament of Treitz to the ileocecal valve. Careful inspection showed that there was no evidence of malrotation. However, the base of the small bowel mesentery was very narrow, which allowed twisting to occur (Fig 2). To prevent further episodes of volvulus, the jejunum was pexed to the colon in the left upper quadrant, and the distal ileum was pexed to the ascending colon.
INTESTINAL VOLVULUS FROM MESENTERIC DEFECTS
Fig 2. lntraoperative photograph of case 5. Note the abnormally shortened mesentery at the base of the small intestine. The mesentery between the arrows represents the entire mesenteric root.
Postoperatively, the patient’s intestinal function recovered, and a normal diet was begun. Six months after surgery, the patient’s diet is normal, and she has had no further symptoms.
Case 6 A 3-day-old boy had been noted to have a hypoechoic bowel pattern on prenatal ultrasound. After delivery, the results of the physical examination were normal, with no abdominal distension, pain, or masses. A barium enema showed a meconium plug extending from the rectosigmoid colon to the proximal transverse colon. There was reflux into the terminal ileum, but no intestinal abnormalities. Because of poor feeding, an upper gastrointestinal series was performed, which showed poor gastric emptying with extrinsic compression of the gastric antrum. The extrinsic compression was believed to be secondary to air-filled loops of bowel. The distension worsened, and mild abdominal pain developed. A computed tomography scan of the abdomen showed multiple loops of dilated intestine, believed to be consistent with distal ileal obstruction. At operation there was distal ileal obstruction secondary to intestinal atresia. However. the cause of the atresia was clearly a segmental mesenteric defect in which a volvulus had occurred. The atresia was in continuity, and the abnormal segment of intestine was viable but separated from the remainder of the ileum. The abnormal segment and the atresia were excised, and a primary anastamosis was performed. Shortly after surgery, a normal diet was begun, and the patient was discharged 1 week after surgery. Six months later, he is tolerating a diet appropriate for his age and is growing normally.
DISCUSSION
Intestinal volvulus is a surgical emergency that requires rapid diagnosis and prompt treatment to reduce morbidity and mortality. Recognition of intestinal volvulus before intestinal infarction is the hallmark for minimizing morbidity and mortality. In the pediatric population, intestinal volvulus is most commonly associated with disorders of rotation and fixation.lm4The keys to expeditious diagnosis of malrotation and early surgical intervention are a high index of suspicion and swift radiographic evaluation including appropriate contrast studies. The radiographic
1341
findings in malrotation are well described5-7 and in most cases are easy to recognize. Intestinal volvulus without malrotation is uncommon and is not as easily recognizable as volvulus with malrotation. Thus, the former is associated with a high mortality rate.8 The high complication rate is primarily the result of deIays in diagnosis. The delays are secondary to the diversity of presentations of intestinal volvulus without disorders of malrotation and lack of specific clinical or radiographic features. Furthermore, a wide variety of mesenteric defects can occur during fetal development. These range from lesions involving a short, clearly defined area of the small intestine (segmental defects) to lesions involving the entire base of the mesentery (basilar defects). In his classic study, Dott9 divided intestinal rotation into three stages. During the first stage, the rapidly elongating midgut forms an S-shaped flexure before it begins its return to the abdominal cavity. In the second stage, the intestine returns to the abdominal cavity, completing a 270” counterclockwise turn as it does so. This stage is the most important in the final configuration of the intestines within the peritoneal cavity. During the third stage, little rotation occurs. However, it is during this stage that the mesentery fuses with the posterior abdominal wall, along the line of the superior mesenteric artery. This is a very critical stage in intestinal development, allowing the small intestine, which was originally based on a very narrow pedicle at the origin of the superior mesenteric artery, to develop a wide secondary attachment along the root of the mesentery. This last step in intestinal rotation is key to providing the extensive attachments that make volvulus impossible (Fig 3). Failure of fusion during the third stage of intestinal fixation is the most likely cause when the entire base of the mesentery is involved in the process (Fig 4). There have been other reports of this type of lesion.‘O-I2 However, the etiology of segmental mesenteric defects is not clear. Little has been written about the development of the mesentery, except for the ventral mesentery, which gives rise to the lesser omentum, the falciform ligament, and the visceral peritoneum of the liver. Persistence of the ventral mesentery has been reported, but no other isolated mesenteric defects are present in the literature.13 In this present study, two patients had defects that involved the entire base of the mesentery. The remainder had segmental defects. The etiology of segmental mesenteric defects is unclear. It appears that each of these defects resulted from either excess growth of a small segment of small intestine or the uncontrolled growth
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Fig 3. illustration of the normal, broad-based mesenteric root. It is clear that the broader the base, the more difficult it is for volvulus to occur.
of an isolated segment of mesentery. Either mechanism would have resulted in a portion of intestine having a small segment of mesentery with a narrow base. The small base would allow free movement and twisting of that segment of the intestine (Fig 5). The clinical presentation of these defects depends on the extent of the defect and the age of presentation. All the children with segmental mesenteric defects had signs of obstruction at the time of presentation. In the neonatal period, this defect was
Fig 4. Illustration of an abnormally short mesenteric root. Twisting around such a short base is more probable than a base twisting around of normel length.
BLACK ET AL
misdiagnosed most often as intestinal atresia. The older children were taken to the operating room with intestinal obstruction of an unknown cause. The neonates with basilar mesenteric defects had a clinical presentation indistinguishable from midgut volvulus secondary to intestinal malrotation. The older child in our series with a basilar mesenteric defect posed somewhat of a diagnostic dilemma. She presented with intestinal obstruction on two occasions. Both times the obstruction was believed to be secondary to adhesions even though twisting of the bowel was noted during both operations. In each instance, a normally placed ligament of Treitz lead the surgeon to believing that volvulus was not the reason for the obstruction. Treatment should be individualized. Patients with basilar disease require fixation of the intestine to prevent subsequent twisting. Because the intestine has undergone normal rotation, there are no Ladd bands, and the appendix is in its normal location. Segmental mesenteric defects require resection of the affected bowel. The decision to perform a primary or delayed anastamosis is made at the time of surgery. Since the classic studies of Louw and Barnard,14 interuterine mesenteric vascular catastrophe has been recognized as the cause of intestinal atresia. In 1959, Courtoisrs further demonstrated that if an intestinal loop is isolated and its blood supply is poor, the loop would be reabsorbed. The pathology encountered in our sixth case suggests that segmental mesenteric defects may be the major cause of intestinal atresia. Because these defects appear to be highly prone to twisting and if intrauterine volvulus of intestine occurs (thus compromising the blood supply), intestinal atresia can result. Furthermore, if several segmental defects with volvulus were to occur throughout the small intestine, then multiple atresias would result.
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INTESTINAL VOLVULUS FROM MESENTERIC DEFECTS
The so-called apple core lesion seen in cases of intestinal atresia may be caused by basilar defects, with more extensive intestinal necrosis than that seen with segmental defects. Consideration of mesenteric defects as the major cause of intestinal atresia would
allow all the various lesions observed to be unified under one consistent etiology. Moreover, because colonic mesenteric defects have never been described either antenatally or postnatally, this theory also would explain the rareness of colonic atresia.
REFERENCES 1. Snyder WH, Chaffin L: Embryology and pathology of the intestinal tract: Presentation of 40 cases of malrotation. Ann Surg 140:368-380,1954 2. Stewart DR, Colodny AL, Daggett WC: Malrotation of the bowel in infants and children: A 15year review. Surgery 79:716720,1976 3. Andrassy RJ, Mahour GH: Malrotation of the midgut in infants and children: A 25year experience. Arch Surg 116:158-160, 1981 4. Rescorla FJ, Shedd FJ, Grosfeld JL, et al: Anomalies of intestinal rotation in childhood: Analysis of 447 cases. Surgery 108:710-716,199O 5. Houston CS, Wittenborg MH: Roentgen evaluation of anomalies of rotation and fixation of the bowel in children. Radiology 84:1-18,1965 6. Berdon WE, Baker DH, Bull S, et al: Midgut malrotation and volvulus: Which films are most helpful? Radiology 96:375-383,197O 7. Graines PA, Saunders AJS, Drake D: Midgut malrotation diagnosed by ultrasound. Clin Radio1 38:51-53,1987
8. Yadav K, Nayar PM, Pate1 RV, et al: Volvulus neonatorium without malrotation. J Indian Med Assoc 85:16-19,1987 9. Dott NM: Anomalies of intestinal rotation: Their embryology and surgical aspects, with report of five cases. Br J Surg 11:251-286, 1923 10. Cueto J, Mednoza CB Jr, Easley GW, et al: Volvulus of the entire small intestine without associated mahotation. Arch Surg 96:953-955,1968 11. Wilkinson TS, Stone HH: Intestinal volvulus without malrotation in a four month old infant. Am Surg 33:3665-3666, 1967 12. Usmani SS, Kenigsberg K: Intrauterine volvulus without malrotation. J Pediatr Surg 26:1409-1410,199l 13. Gray SW, Skandalakis JE: Embryology for Surgeons. Philadelphia, PA, Saunders, 1972 14. Louw JH, Barnard CN: Congenital intestinal atresia: Observations on its origin. Lancet 2:1065-1067,1955 15. Courtois R: Les origines foetales des occlusions congenitales grele dites par atresia. J Chir 78:405-409, 1959