Constipation and Abdominal Pain in a 2-Year-Old Girl
A 2-year-old girl, born at 30 weeks’ gestation with chronic lung disease, presented to the emergency department (ED) with concerns for constipation. She had been having ball-like stools for the past month.
She had been seen previously in the ED for decreased oral intake and constipation. She had been given an enema, prescribed polyethylene glycol 3350 laxative solution, and discharged home. The mother reported that the girl was now irritable and that she said her abdomen hurts.
On physical examination, the girl’s abdomen was firm and distended. Radiographs of the kidneys, ureters, and bladder (KUB) showed moderate stool burden. A computed tomography (CT) scan of the abdomen and pelvis was performed, the results of which are shown in Figures 1-3.
What is causing the girl’s bowel symptoms?
A. Functional constipation
B. Intussusception
C. Choledochal cyst
D. Appendicitis
(Answer and discussion on next page)
Answer: C, choledochal cyst
A choledochal cyst is a congenital anomaly of the biliary tract. It is a single cystic dilation or multiple dilations of some portion of the biliary tree. The incidence is 1 in 100,000 to 500,000.1 It occurs most commonly in the Asian population, with 50% to 70% of reported cases in Japanese.2 Choledochal cysts occur more often in children, and they more often affect girls and women than boys and men, with a 3:1 predilection.1
Choledochal cysts are categorized into 5 types based on location and number; type 1 cysts are subcategorized as 1A, 1B, or 1C, while type 4 cysts are subclassified as 4A or 4B. From 50% to 70% of choledochal cysts are type 1—a single extrahepatic cyst of the common biliary duct. Type 4A cysts (such as the our patient’s) comprise numerous dilations of the intrahepatic and extrahepatic bile ducts, while type 4B cysts comprise numerous dilatations but involve only the extrahepatic bile ducts.
Figure 1. Abdominal and pelvic transverse view CT image demonstrating a choledochal cyst.
Figure 2. CT Abdominal and pelvic coronal view CT.
Figure 3. CT Abdominal and pelvic sagittal view.
The etiology of choledochal cysts has been debated, withmany experts theorizing that they form from an unequal proliferation of embryonic biliary epithelial cells, or from prenatal ductal obstruction. Under further review, RNA from reoviruses has been isolated from infant biliary tissues after resection.
Of congenital cases of choledochal cyst, 60% to 90% are secondary to an abnormal junction between the pancreatic and biliary systems.3 The common bile duct and pancreatic duct form a ductal channel before terminating in the duodenal lumen. Reflux of pancreatic secretions causes biliary damage, leading to epithelial inflammation, duct distention, and cyst formation.
Patients with choledochal cysts can present with right upper quadrant pain, pruritus, jaundice, acholic stools, or an abdominal mass. The most significant laboratory finding is hyperbilirubinemia suggestive of obstructive jaundice.4,5 Abdominal ultrasonography can aid in the diagnosis. The gold standard diagnostic imaging is magnetic resonance cholangiopancreatography.
Surgical resection is therapeutic.3 The Kasai procedure is the most common surgical approach, in which a cholecystectomy with biliary tree removal and hepaticojejunostomy is performed. Complications can include postsurgical infection, adhesions, and strictures.
The rate of malignancy (cholangiocarcinoma and adenocarcinoma) is 20 to 30 times higher in patients with choledochal cysts than in the general population. It is thought that a mixture of bile and pancreatic enzymes promotes dysplasia and metaplasia, progressing to malignancy. These outcomes most commonly occur with type 1 and 4 cysts, and the recurrence rate is high even after surgical resection of the entire biliary system.3 n
Lauren Astrug, MD, is a resident in the Department of Pediatrics, Division of General Pediatrics, at Children’s Medical Center in Dallas, Texas.
Daniel Thimann, MD, is a fellow in the Department of Pediatrics, Division of Emergency Medicine, at Children’s Medical Center.
Michael Baldovsky, DO, is an assistant professor in the Department of Pediatrics, Division of Emergency Medicine, at Children’s Medical Center.
References
1. Sawyer MAJ. Choledochal cysts. Medscape Web page. http://emedicine.medscape.com/article/172099-overview. Updated April 1, 2014. Accessed July 14, 2014.
2. Miyano T, Yamataka A. Choledochal cysts. Curr Opin Pediatr. 1997;9(3):283-288.
3. Ohashi T, Wakai T, Kubota M et al. Risk of subsequent biliary malignancy in patients undergoing cyst excision for congenital choledochal cysts. J Gastroenterol Hepatol. 2013;28(2):243-247.
4. Brumbaugh D, Mack C. Conjugated hyperbilirubinemia in children. Pediatr Rev. 2012;33(7):291-302.
5. Davis AR, Rosenthal P, Escobar GJ, Newman TB. Interpreting conjugated bilirubin levels in newborns. J Pediatr. 2011;158(4):562-565.