Table 1. [Differential Diagnosis of Megacystis-Microcolon-Intestinal Hypoperistalsis Syndrome (MMIHS)]. - GeneReviews®

Presenting Symptom in MMIHS	Differential Diagnosis	Distinguishing Clinical Features
Fetal megacystis	Lower urinary tract obstruction	Imaging or cystoscopy shows posterior urethral valves or urethral atresia/stenosis.
Obstructive symptoms (e.g., abdominal distention, bilious emesis, failure to pass meconium)	Hirschsprung disease	Absence of megacystis; rectal biopsy shows absence of ganglion cells
Small bowel atresia or colonic atresia	Absence of microcolon; isolated colonic atresia w/out megacystis
Anorectal malformation	Abnormal anal position/caliber; clinical features of VACTERL association
Meconium ileus/plug	Family history of cystic fibrosis; failure to thrive; pancreatic insufficiency
Hypothyroidism	Absence of megacystis & microcolon; laboratory evidence of hypothyroidism
Sepsis	Absence of megacystis & microcolon; laboratory evidence of sepsis
Prenatal & intrapartum medication exposure (e.g., magnesium sulfate, opioids)	Absence of megacystis & microcolon
Diabetic embryopathy	Absence of megacystis
Fetal megacystis & obstructive symptoms	Prune belly sequence ¹	Absence of microcolon
Multisystemic smooth muscle dysfunction syndrome (MSMDS) ¹	Mydriasis, vascular abnormalities, absence of microcolon

Presenting Symptom in MMIHS

Differential Diagnosis

Distinguishing Clinical Features

Fetal megacystis

Lower urinary tract obstruction

Imaging or cystoscopy shows posterior urethral valves or urethral atresia/stenosis.

Obstructive symptoms
(e.g., abdominal distention, bilious emesis, failure to pass meconium)

Hirschsprung disease

Absence of megacystis; rectal biopsy shows absence of ganglion cells

Small bowel atresia or colonic atresia

Absence of microcolon; isolated colonic atresia w/out megacystis

Anorectal malformation

Abnormal anal position/caliber; clinical features of VACTERL association

Meconium ileus/plug

Family history of cystic fibrosis; failure to thrive; pancreatic insufficiency

Hypothyroidism

Absence of megacystis & microcolon; laboratory evidence of hypothyroidism

Sepsis

Absence of megacystis & microcolon; laboratory evidence of sepsis

Prenatal & intrapartum medication exposure (e.g., magnesium sulfate, opioids)

Absence of megacystis & microcolon

Diabetic embryopathy

Absence of megacystis

Fetal megacystis & obstructive symptoms

Prune belly sequence ¹

Absence of microcolon

Multisystemic smooth muscle dysfunction syndrome (MSMDS) ¹

Mydriasis, vascular abnormalities, absence of microcolon

From: Megacystis-Microcolon-Intestinal Hypoperistalsis Syndrome Overview

GeneReviews^® [Internet].

Adam MP, Feldman J, Mirzaa GM, et al., editors.

Seattle (WA): University of Washington, Seattle; 1993-2024.

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