Atypical genitalia in neonates

Last reviewed: 6 Sep 2022
Last updated: 04 Feb 2022

Summary

Definition

History and exam

Key diagnostic factors

  • atypical genitalia with no palpable gonads
  • atypical genitalia with one palpable gonad
  • atypical genitalia with bilaterally palpable gonads
  • penile length <2.5 cm in a phenotypic male
  • clitoris >1 cm in a phenotypic female
  • hypospadias and undescended testes or separation of scrotal sacs
  • urethral opening at base of phallus
More key diagnostic factors

Other diagnostic factors

  • hypotension and vomiting
  • dysmorphic facial features
Other diagnostic factors

Risk factors

  • family history
More risk factors

Diagnostic investigations

1st investigations to order

  • chromosome analysis (karyotype)
  • serum electrolytes and glucose
  • pelvic ultrasound
More 1st investigations to order

Investigations to consider

  • serum 17 hydroxyprogesterone
  • plasma renin activity
  • serum 11 deoxycortisol and 11 deoxycorticosterone
  • serum testosterone
  • serum dihydrotestosterone
  • serum LH and follicle-stimulating hormone (FSH)
  • adrenocorticotropic hormone (ACTH) stimulation test
  • human chorionic gonadotrophin (hCG) stimulation test
  • Müllerian-inhibiting substance (MIS) or anti-Müllerian hormone (AMH)
  • urine steroid profile
More investigations to consider

Treatment algorithm

INITIAL

all neonates presenting with atypical genitalia

ACUTE

46,XX: congenital adrenal hyperplasia secondary to 21 hydroxylase deficiency (at presentation)

46,XY

ONGOING

46,XX: congenital adrenal hyperplasia secondary to 21 hydroxylase deficiency (following sex assignment)

46,XY

45,X/46,XY mixed gonadal dysgenesis

Contributors

Authors

Justin H Davies, MD, FRCPCH, MRCP

Consultant Paediatric Endocrinologist

Honorary Senior Lecturer

University of Southampton

Southampton

UK

Disclosures

JD is chair of the British Society for Paediatric Endocrinology and Diabetes and a medical advisor to the Child Growth Foundation. He has received a travel bursary from Novo Nordisk and grants from the European Society for Paediatric Endocrinology and the Child Growth Foundation.

Gemma Watts, BMS, MRCPCH

Specialist Registrar in Paediatric Endocrinology

Department of Paediatrics

University Hospitals Southampton NHS Trust

Southampton

UK

Disclosures

GW declares that she has no competing interests.

Acknowledgements

Dr Justin Davies and Dr Gemma Watts would like to gratefully acknowledge Dr Ingrid A. Holm, a previous contributor to this topic. IAH declares that she has no competing interests.

Peer reviewers

Paul Saenger, MD, MACE

Professor of Pediatrics

Department of Pediatrics (Endocrinology)

Montefiore Medical Center

Albert Einstein College of Medicine

New York

NY

Disclosures

PS declares that he has no competing interests.

Mary M. Lee, MD

Professor of Pediatrics and Cell Biology

Vice-Chair of Academic Affairs in Pediatrics

Pediatric Endocrine Division

UMass Medical School

Worcester

MA

Disclosures

MML declares that she has no competing interests.

Patricia Y. Fechner, MD

Associate Professor Pediatrics

Pediatric Endocrinology

University of WA

Medical Director of DSD Program

Seattle Children’s Hospital

Seattle

WA

Disclosures

PYF declares that she has no competing interests.

  • Atypical genitalia in neonates images
  • Differentials

    • Micropenis due to another cause
    • Unilateral undescended testis (cryptorchidism)
    More Differentials
  • Guidelines

    • UK guidance on the initial evaluation of a suspected difference or disorder of sex development (revised 2021)
    • Guidelines on paediatric urology
    More Guidelines
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