Pelvic Inflammatory Disease Ultrasound

Pelvic Inflammatory Disease (PID)

Introduction

Pelvic Inflammatory Disease (PID) is an infection of the female upper genital tract including the endometrium, fallopian tubes, ovaries, and adjacent pelvic structures. Ultrasound plays a crucial role in diagnosis and assessment of complications. This article details the sonographic appearance of PID with emphasis on:

  1. Acute salpingitis - Inflammation of fallopian tubes
  2. Pyosalpinx - Pus-filled dilated tube
  3. Tubo-ovarian abscess (TOA) - Advanced infection with complex adnexal mass
  4. Oophoritis - Ovarian inflammation
  5. Endometritis - Uterine lining inflammation
  6. Pelvic peritonitis - Inflammation extending beyond reproductive organs

1. Acute Salpingitis

Early stage PID characterized by fallopian tube inflammation without significant fluid accumulation.

Pathophysiology

Ascending infection (typically N. gonorrhoeae or C. trachomatis) → endosalpingeal edema → ciliary dysfunction → inflammatory exudate.

Ultrasound Findings

  • Tubal wall thickening (>5mm)
  • Incomplete septae within dilated tube ("cogwheel sign")
  • Hypervascularity on Doppler imaging
  • Pelvic free fluid (often complex)
  • Ovarian stromal edema (enlarged, hypoechoic ovaries)
Acute salpingitis

Acute Salpingitis

  • Thickened tubal walls (>5mm)
  • Incomplete septations
Cogwheel sign

Cogwheel Sign

  • Transverse view of inflamed tube (red arrow)
  • Characteristic "cogwheel" appearance
  • UT is the uterus


2. Pyosalpinx

Advanced salpingitis with pus accumulation in the fallopian tube lumen.

Clinical Features

Severe pelvic pain, fever, cervical motion tenderness. Risk factors include multiple sexual partners, IUD use, and prior PID.

Ultrasound Findings

  • Dilated tube (>10mm diameter) with thick walls
  • Low-level internal echoes (pus content)
  • "Beads-on-a-string" sign - hyperechoic mucosal folds in distended tube
  • Fluid-debris level (pathognomonic)
  • Increased vascularity in tubal walls
Pyosalpinx

Pyosalpinx

  • Dilated tube with thick walls
  • Low-level internal echoes
Beads on string sign

Beads-on-a-string Sign

  • Hyperechoic mucosal folds
  • Distended fallopian tube
  • Hypervascularity on color Doppler

3. Tubo-Ovararian Abscess (TOA)

Most severe form of PID where infection spreads beyond tubes to involve ovaries and adjacent structures.

Ultrasound Findings

  • Complex adnexal mass with thick irregular walls
  • Septations and internal debris
  • Indistinct ovarian borders (ovary incorporated into mass)
  • Gas bubbles (hyperechoic foci with dirty shadowing)
  • Pelvic fat stranding (hyperechoic peritoneum)

Clinical Significance

Requires IV antibiotics ± drainage. Rupture can lead to life-threatening sepsis.

Tubo-ovarian abscess

Tubo-Ovarian Abscess

  • Complex adnexal mass
  • Thick irregular walls
TOA with gas

TOA with Gas

  • Hyperechoic gas foci
  • "Dirty" posterior shadowing

4. Oophoritis

Isolated ovarian inflammation, often coexisting with salpingitis in PID.

Ultrasound Findings

  • Ovarian enlargement (volume >10cm³)
  • Stromal edema (diffuse hypoechogenicity)
  • Hypervascularity on Doppler ("fire ring" pattern)
  • Follicular wall thickening (>3mm)
  • Periovarian fat stranding (hyperechoic surrounding tissue)

Clinical Pearls

  • Often bilateral but may be asymmetric
  • Differentiate from ovarian torsion (preserved venous flow in oophoritis)
  • May progress to TOA if untreated
Oophoritis with stromal edema

Oophoritis with Stromal Edema

  • Enlarged ovary (49.03cm³)
  • Diffuse hypoechoic stroma
Oophoritis hypervascularity

Oophoritis Hypervascularity

  • "Fire ring" pattern on Doppler
  • Resistive Index <0.5

5. Endometritis

Inflammation of the endometrial lining, often coexisting with salpingitis.

Ultrasound Findings

  • Endometrial thickening (>8mm in proliferative phase)
  • Intrauterine fluid (complex echogenicity)
  • Air in endometrial cavity (postpartum cases)
  • Hypervascular endometrium on Doppler
  • Irregular endometrial-myometrial interface

Risk Factors

Recent childbirth, miscarriage, IUD insertion, or instrumentation of uterus.

Endometritis

Endometritis

  • Thickened endometrium
  • Intrauterine fluid (asterisk)
Endometritis with air

Endometritis with Air

  • Hyperechoic air foci
  • Postpartum patient


6. Fitz-Hugh-Curtis Syndrome

Perihepatitis complication of PID causing right upper quadrant pain ("violin string" adhesions).

Ultrasound Findings

  • Perihepatic fluid (often complex)
  • Thickened gallbladder wall (reactive change)
  • Hepatic capsular enhancement on Doppler
  • Adhesions between liver and diaphragm

Clinical Pearls

Consider in young women with RUQ pain + cervical motion tenderness. Differentiate from cholecystitis.

Fitz-Hugh-Curtis

Fitz-Hugh-Curtis

  • Perihepatic fluid (red arrow)
  • Thickened hepatic capsule
Violin string adhesions

Violin String Adhesions

  • Laparoscopic view
  • Thin fibrous bands

Differential Diagnosis

Condition Key Differentiating Features
Ectopic pregnancy Positive β-hCG, decidual reaction, no fever
Endometriosis Cyclic pain, "kissing ovaries," no infection signs
Ovarian torsion Absent venous flow, twisted vascular pedicle
Appendicitis Non-gynecologic pain, dilated appendix
Diverticulitis Colonic wall thickening, pericolic fat stranding

Management Guidelines

Mild PID

  • Outpatient treatment
  • Ceftriaxone 250mg IM + Doxycycline 100mg BID x14d
  • Metronidazole 500mg BID x14d (if anaerobes suspected)

Severe PID/TOA

  • Hospital admission
  • IV Cefoxitin/Ertapenem + Doxycycline
  • Ultrasound-guided drainage if >5cm
  • Surgical intervention if rupture suspected
.

References

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