2003-02-20-21 Midgut volvulus © Thomas www.thefetus.net/
D. Thomas°, J.P. Goolaerts*, L. Watkins°, C. Autin°, P. Barlow*
° Hôpitaux Iris Sud, Brussel Belgium * Hôpital Universitaire St Pierre Brussel Belgium
A 27-year-old G1P0 presented at 33 weeks 6 days of gestation.Chief complaint was abscence of fetal movement for tha last 24 hours. This pregnancy had been uneventful until then.
Non-stress test (NST) suggested fetal distress and fetal anemia: late decelerations, fetal tachycardia (160 beats/min), absence of reactivity and sinusoidal rythm. The biophysical profile revealed a complete absence of gross body and breathing movements, the amniotic fluid was mildly increased.
Ultrasound examination was performed. Head and femur measurements were the expected for gestational age. Surprisingly, the abdominal circumference was on the 95th percentile. The fetal abdomen contained an enlarged stomach and a few dilated bowel loops with a maximal diameter of 16,1mm and with hyperperistalism (fig2) .
There was a convoluted mass in the midabdomen. It had the typical aspect of a whirlpool or snail configuration, without any peristalsis (fig 3, video clip).The color/power Doppler failed to find any signal in the center of the whirlpool image. There is also a short video-clip available.
There was mild ascites between the dilated bowel loops. The colon was not recognized during the whole examination.
Fetal Doppler study showed absent end-diastolic flow in the umbilical artery. Besides that, the resistance index was normal in fetal middle cerebral artery, but there was a marked increase in the maximal systolic blood flow velocity ( 87,7 cm/sec) in the middle cerebral artery.
At this time the presumptive diagnosis was: Fetal midgut volvulus with acute fetal distress and probably fetal anemia. The patient was referred to a tertiary center where a pediatric surgeon could perform immediate surgery. An emergency cesarean section was performed and permitted the birth of a female infant weighing 2350gr with Apgar scores of 1 and 7 at 1 and 5 min respectively. The umbilical artery pH was 7,31 and BE –4. The hemoglobin concentration in the umbilical vein was 9gr /100 ml. At the time of birth, the baby was completely contracted and appeared with a profound painful rictus. Frequent apnea prompted immediate endotracheal intubation. Laparotomy was performed after vital parameter stabilization. The midportion of the small bowel was twisted seven times and appeared gangrenous. No malrotation or atresia were noted during the procedure 40 cm of small bowel had to be resected. Ileostomy and jejunostomy were also necessary. The gut continuity was restablished after one month. 6 months later, the baby has no neurological sequelae, but suffers of short-gut syndrome and requires long periods of hyperalimentation
Incidence of small bowel occlusion: approximately 1/3000 births (1). Only a few cases of fetal midgut volvulus have been reported. The great majority of fetal mid gut volvulus have been reported during the third trimester of pregnancy .
Etiology: The delayed return of the fetal midgut in the abdomen has been reported to result in midgut volvulus as well as other midgut pathologies as intestinal obstruction and short bowel syndrome (2) . Normally the midgut returns into the abdominal cavity when the embryo reaches 40mm of length. The reentery of the small bowel does not occur in a normal fashion and the mesentery does not fix normally to the posterior wall (3). In this situation neither atresia nor gut malrotation are found.
A case of absence of the small intestine musculature associated with intrauterine volvulus has been reported by Morikawa et al (4), they speculate that the etiology of the muscle defect could be secondary to an ischemic event.
Intestinal malrotation associated with a short mesentery predisposes to midgut volvulus as well as intestinal atresia: by the way of an increased peristaltism, volvulus appears above the atresia.
Location of the volvulus: The volvulus occurs between the proximal jejunum and the distal ileum. Magnetic resonance imaging has proved to be helpful in determining the precise site of obstruction because the colon and the small bowel have specific prenatal appearances ( this is not the case for ultrasonography) and to detect hemorrhagic necrosis of the involved bowel (5,6).
Clinical findings: As previously pointed out by some authors, at first the pregnant patient complains of an acute decrease in fetal movement (7); and secondly the antepartum fetal heart rate monitoring shows abnormalities such as late decelerations and poor variability (2) . Some authors (8) have emphasized that intrauterine volvulus is a unique situation in which uteroplacental insufficiency is fetal in origin. In our case no asphyxia was noticed at birth, but the fetus presented a serious anemia wich was probably responsible for the abnormal non-stress-test.
Sonographic diagnosis: Classically in case of small bowel obstruction, multiple filled loops of small bowel appear abnormally dilated. They can present strong peristaltic movements. The upper normal value of small bowel in the second trimester is 7mm in diameter and 15mm in length (9).In case of volvulus, Yoo et al (10) have described the specific whirlpool or snail sign produced by the twisted bowel loop and mesentery around the main superior mesenteric artery. There is no peristaltic movement in the “whirlpool”. They have suggested that the visualization of mesenteric vessels by color doppler examination may predict the necrosis of the involved gut. We noted an increase in the peristaltism proximal to the loops presenting the whirlpool sign. When there is an associated atresia, a dilated bowel loop appears below the twisted loop as a mass ”shaped like a coffee bean” (10). We think that doppler investigation in the middle cerebral artery showing an increased systolic velocity may help to suspect a fetal anemia related to blood sequestration in necrosed bowel loops (11).
Polyhydramnios is a classical sonographic sign of obstruction, but is not always present (2,12), Heydanus et al (13) report this sign in 71% of small bowel obstructions. Kimble et al report them in only 24% of atresias of the small intestine, even when the atresia is in the proximal jejunum. (14).
Peritoneal calcification and pseudocyst are described when perforation occurs (15).
Differential diagnosis: all situations that lead to bowel obstruction: jejunal atresia, ileal atresia, cystic fibrosis with meconium ileus, and meconium pseudocyst , small bowel duplication (13). In a series by Heydanus et al ( 13), none of them revealed associated anomalies nor abnormal karyotype . Sweeneney et al (16) stipulate that jejunal atresias are more likely associated with other congenital anomalies (42%) than ileal atresias (2%). They conclude that vascular injury is responsible for the majority of jejunal atresias and early malformative processes for the minority as in the adriamycin rat model.
Prenatal testing can be offered in case of cystic fibrosis.
Another very rare inherited enteropathy: congenital microvillous inclusion disease (severe secretory diarrhea) should be considered in such cases (17). Fetal ultrasound scanning gives an appearence of intestinal dilatation with polyhydramnios. Definitive diagnosis is established after birth by small bowel biopsy. A normal colonic appearance may help to distinguish non-obstructive and obstructive causes of small bowel obstruction.
Other intra-abdominal echolucent cystic mass must be considered in differential diagnosis: multicystic kidneys, hydronephrosis, hydroureter, hydrometrocolpos, choledocal cyst, mesenteric cyst, omental cyst and ovarian cyst.
Clinical evolution: Perforation of the intestine and pseudocyst formation have been reported in association with in utero intestinal volvulus(18 ).
Hydrops fetalis has been described in association with small bowel volvulus (19). The predisposing factors are: the chronic blood loss, the haemolysis due to the disseminated intravascular coagulation, the decreased oncotic pressure, and the loss of plasma volume(19).
Midgut volvulus is associated with premature delivery. De Felice et al (20) offer the hypothesis that acute fetal stress and fetal pain can activate both fetal-placental adrenal and hypothalamic stress hormones leading to premature uterine activity. Ashworth gives the same explanation to the cause of miscarriage in the second trimester of 4 pregnancies in which the “fresh”fetuses were affected by a volvulus of the small intestine (21).
The mortality rate is high (22). To our knowledge, including this case, only 9 out of 15 reported cases have survived.
Prognosis: This depends on the extent of the ischemia and infarction of the small bowel at the time of diagnosis and the term of pregnancy at the time of diagnosis. Some patients have been followed by frequent NST and ultrasounds with the aim of not intervening until lung maturity was documented (23). The patient should be delivered in a tertiary center where a pediatric surgeon and a neonatal intensive care unit are available. A trial of vaginal delivery or an elective cesarean section has to be chosen, depending of the fetal distress. Some authors suggest that elective cesarean section could be less traumatic for such a premature and handicapped neonate (24).
Conclusion: Fetal midgut volvulus has a specific clinico-echographic presentation. The main complaint of the pregnant woman is the absence of fetal movement. Non-stress-test can show different stages of fetal distress. The ultrasound examination usually gives the diagnosis by the typical image of whirlpool or snail configuration, without peristalism, and placed centrally in the abdomen. The absence of blood flow by doppler exploration in the centre of the mass suggests gut ischemia. Intestinal necrosis and blood sequestration can be diagnosed by the search for fetal anemia in the observation of non-stress-test and confirmed by the exploration of doppler velocity in middle cerebral artery. The timing of delivery depends of fetal lung maturity, fetal distress and ultrasound appearance of the fetal gut. Delivery must take place in a tertiary center because immediate surgical correction of this anomaly is indispensable.
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