Chorionic Bump in Early Pregnancy

Department of Radiodiagnosis

Aadhar Health Institute, Hisar

Consultants

Dr. Priyanka Goyal, Dr. Pooja Batra, Dr. Lovekesh Bhatia, Dr. Shweta,

Residents

Dr. Raveesh, Dr. Kshitijaa, Dr. Neetika, Dr. Priya

Case Introduction

A 28-year-old female presented for a routine early pregnancy ultrasound at 9 weeks of gestation.

USG Images

Ultrasound Findings

  • Single live intrauterine pregnancy

  • Cardiac activity present

  • A well-marginated heteroechoic lesion projecting into the gestational sac from the chorionic wall

  • No internal vascularity on Color Doppler

  • No subchorionic hematoma or free fluid

Introduction

A chorionic bump is a focal, convex, nodular bulge arising from the chorionic surface and projecting into the gestational sac. It usually shows mixed or hypoechoic internal echoes.

It may represent a small hematoma bulging into the gestational sac or a resorbing anembryonic (failed) second gestation. It is an uncommon ultrasound finding, seen in approximately 0.4–0.7% of pregnancies before 10 weeks.

Pathology

Primary hypothesis:

  • Focal hematoma within the chorionic plate causing outward bulging into the gestational sac

Alternative theories:

  • Abnormal placentation or implantation site reaction

  • Local vascular malformation or thrombosis within chorionic villi

  • Focal decidual necrosis due to poor perfusion

  • Area of early chorionic injury compromising trophoblastic function if extensive

Radiological Features

Ultrasound:

  • Irregular, convex soft-tissue bulge projecting from the choriodecidual surface

  • Isoechoic or heteroechoic compared to chorion

  • Avascular on Color Doppler

  • No associated subchorionic hematoma

MRI:

  • May show T1 hyperintensity suggesting hemorrhagic content

Differential Diagnosis

Entity Key Imaging Features
Chorionic bump Localized convex echogenic/heteroechoic bulge projecting into gestational sac; avascular
Subchorionic hematoma Crescent-shaped hypoechoic collection peripheral to gestational sac
Decidual reaction Uniform, symmetrical echogenic thickening around gestational sac
Embryonic/Fetal pole Definite structure with cardiac activity
Decidual cyst Small anechoic cystic lesion within decidua

Treatment & Prognosis

No specific treatment is required; close sonographic follow-up is recommended.
Chorionic bump is associated with a guarded prognosis in early pregnancy. The risk of miscarriage is approximately twice that of normal pregnancies.
Studies report a 62–65% overall live birth rate, improving to approximately 83% in the absence of other abnormalities. Multiple chorionic bumps are associated with poor outcomes, with reported fetal loss approaching 100%.