9.2 Endometritis, Surgical Site Infections, UTI & Mastitis

9.2 Endometritis, Surgical Site Infections, UTI & Mastitis

Puerperal infections remain a major cause of preventable postpartum maternal morbidity and readmission. The denuded placental implantation site, extensive tissue trauma, altered vaginal microbiota, and surgical incisions create prime portals of entry for microbial pathogens. Prompt identification and targeted antimicrobial therapy are vital to prevent localized pelvic infections from escalating into pelvic peritonitis, septic pelvic thrombophlebitis, or systemic sepsis.

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Definition of Puerperal Morbidity & Physiologic Leukocytosis

Formal Definition of Puerperal Infection

The standard international and CDC/ACOG definition of puerperal morbidity is:

An oral temperature of >= 38.0°C (100.4°F) occurring on any 2 of the first 10 days postpartum, excluding the first 24 hours.

• The First 24-Hour Exclusion Rule: Transient maternal temperature elevations up to 38.0°C during the first 24 hours following birth are common and typically reflect muscular exertion during labor, dehydration, and normal postpartum tissue resorption. However, a temperature >= 38.5°C to 39.0°C at any time—even within the first 24 hours—warrants immediate clinical evaluation for acute infection (such as intraamniotic infection or early bacteremia).

Interpreting Postpartum Leukocytosis: Left Shift vs. Normal Physiology

During labor and the immediate puerperium, physical stress, catecholamine surge, and tissue trauma induce a marked physiological demargination of polymorphonuclear leukocytes.

• Normal Puerperal WBC Count: White blood cell (WBC) counts commonly rise to 20,000 to 25,000/mcL (and occasionally up to 30,000/mcL) during the first 24 to 48 hours without underlying infection.
• Identifying True Infection: A diagnosis of infection cannot rely solely on the total WBC count. Clinicians must evaluate for a "left shift" (bandemia: immature band forms > 10% of total leukocytes) in conjunction with persistent fever, resting maternal tachycardia (> 100 bpm), localized tenderness, or foul drainage.

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Postpartum Endometritis

Pathophysiology & Predisposing Risk Factors

Endometritis (endomyometritis) is an infection of the decidua, myometrium, and adjacent parametrial tissues. It is predominantly polymicrobial, involving an ascending mixture of aerobic and anaerobic genital tract flora: Group B Streptococcus, Enterococcus faecalis, Escherichia coli, Klebsiella pneumoniae, Bacteroides fragilis, and Peptostreptococcus species.

Clinical Presentation & Diagnostic Findings

Endometritis typically manifests between postpartum days 2 and 5 (earlier in post-cesarean patients):

• Fever: Temperature spikes >= 38.0°C (100.4°F), often accompanied by chills and diaphoresis.
• Uterine Fundal Tenderness: Exquisite, localized tenderness on gentle bimanual examination or abdominal palpation of the uterine fundus.
• Lochia Characteristics: Copious, purulent, foul-smelling lochia. (Diagnostic Caveat: Group A beta-hemolytic Streptococcus [GAS] endometritis often presents with scant, odorless lochia, high spiking fevers, rapid toxic shock progression, and severe prostration).
• Subinvolution: The uterus remains boggy, soft, and higher than expected for the postpartum day.
• Maternal Tachycardia: Resting pulse rate > 100 bpm proportional to the fever spike.

Pharmacologic Protocols: The Gold Standard Regimen

Endometritis requires prompt broad-spectrum intravenous antimicrobial therapy:

1. First-Line IV Antimicrobial Regimen:
   • Clindamycin: 900 mg IV every 8 hours (provides potent coverage against anaerobes and Gram-positive cocci).
   • Gentamicin: 1.5 mg/kg IV every 8 hours (or high-dose once-daily 5 mg/kg IV every 24 hours; provides coverage against Gram-negative enterics).
   • Success Rate: This combination cures 90% to 95% of postpartum endometritis cases.
2. Addition of Ampicillin (The Triple Regimen):
   • If the patient remains febrile after 48 to 72 hours of clindamycin and gentamicin, Ampicillin 2 g IV every 6 hours is added to cover resistant Enterococcus faecalis.
3. Discontinuation Criteria:
   • Intravenous therapy is continued until the patient is afebrile (< 37.8°C / 100.0°F) and clinically asymptomatic for 24 to 48 hours.
   • No Oral Antibiotics Needed: Randomized trials demonstrate that transitioning to oral antibiotics following successful clinical resolution of IV therapy provides no additional benefit and is not recommended.

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Surgical Site Infections: Cesarean Wounds & Perineal Lacerations

Classification & REEDA Assessment Scale

Surgical site infections (SSIs) occur in 3% to 15% of cesarean births and 1% to 3% of perineal repairs. Nursing assessment must utilize the validated REEDA scale:

• R - Redness (Erythema): Superficial erythema extending > 2 cm beyond the wound border indicates active cellulitis.
• E - Edema: Tense, shiny induration or swelling along incision margins.
• E - Ecchymosis: Traumatic bruising vs. expanding hematoma.
• D - Discharge: Normal clear serous exudate vs. cloudy, foul, purulent drainage.
• A - Approximation: Snugly approximated wound edges vs. wound separation, gaping, or full-thickness dehiscence.

Cesarean Incisional SSI Management

• Superficial Incisional Infection: Involves skin and subcutaneous tissue. Management requires opening the incision to the level of the fascia, draining purulent fluid or hematomas, irrigating copiously, debriding devitalized tissue, and obtaining aerobic and anaerobic cultures.
• Fascial Integrity Verification: The examining clinician must inspect and palpate the rectus abdominis fascia to ensure it remains intact. If the fascia has separated (fascial dehiscence or evisceration), emergency surgical repair in the operating room is mandatory.
• Wound Healing: Wounds opened for drainage are packed with saline-moistened sterile gauze (wet-to-dry dressings) or treated with negative-pressure wound therapy (wound VAC) to facilitate healing by secondary intention or delayed primary closure.

Perineal Episiotomy & Laceration Infections

• Clinical Presentation: Intense, throbbing perineal pain, pain out of proportion to exam, difficulty sitting, purulent drainage from suture lines, and suture breakdown.
• Management: Remove remaining sutures, probe and irrigate the wound space, debride necrotic tissue, prescribe sitz baths 2 to 3 times daily, provide stool softeners, and administer oral broad-spectrum antibiotics (e.g., amoxicillin-clavulanate).

LIFE-THREATENING EMERGENCY: Necrotizing Fasciitis
A rare, fulminant polymicrobial infection of the subcutaneous tissue and deep fascial planes. Suspect necrotizing fasciitis when a perineal or abdominal wound displays disproportionate agonizing pain, rapid violaceous or bronze skin discoloration, tense bullae, cutaneous anesthesia (due to nerve destruction), crepitus on palpation, and rapid septic shock. Management requires immediate surgical wide radical debridement and triple IV broad-spectrum antibiotics.

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Postpartum Urinary Tract Infections: Cystitis vs. Pyelonephritis

Pathophysiological Vulnerability in the Puerperium

During the postpartum period, the maternal urinary tract experiences marked hypotonia, ureteral dilation, and diminished bladder sensation resulting from elevated progesterone levels, intrapartum bladder trauma, and regional anesthesia. Urinary retention, bladder overdistension, and indwelling catheterization create an optimal environment for ascending bacterial growth, primarily Escherichia coli (75% to 80% of cases).

Differentiating Lower vs. Upper Urinary Tract Infection

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Lactational Mastitis & Breast Abscess

Inflammatory mastitis causes focal erythema, edema, and pain with variable systemic symptoms. Continue physiologic breastfeeding, apply ice, use an NSAID when safe, rest, and avoid deep massage or extra pumping “to empty,” which can worsen edema and oversupply. Persistent or worsening systemic illness or focal inflammation suggests bacterial mastitis and requires clinical evaluation and an antibiotic selected for likely organisms, allergy, and local resistance.

Suspect phlegmon or abscess when a mass persists, fever recurs, or a fluctuant collection develops. Ultrasound and drainage are often needed, with culture when indicated. Milk is generally safe for a healthy term infant; abrupt weaning can worsen stasis. Sepsis, rapidly spreading change, crepitus, hemodynamic instability, or failure to improve requires urgent escalation.

Clinical Pearls & Exam Alerts

EXAM ALERT: Continuing Lactation During Mastitis
Exam questions routinely present a mother with classic mastitis symptoms (fever, chills, unilateral wedge of erythema) who asks whether she should stop breastfeeding to protect her infant. The correct nursing action is always to instruct the patient to continue frequent nursing or pumping from the affected breast, starting feeds on the unaffected side to initiate the let-down reflex if pain is severe, followed by thorough emptying of the affected side.

CLINICAL PEARL: CVA Tenderness Signals Pyelonephritis
A postpartum patient reporting dysuria, urinary frequency, and high fevers who displays costovertebral angle (CVA) tenderness on gentle percussion has ascended infection (acute pyelonephritis). Do not treat as an outpatient cystitis with oral antibiotics; the patient requires hospital admission for intravenous fluids and parenteral antibiotics to prevent septic shock.

CLINICAL PEARL: Suspecting a Breast Abscess
When a patient with lactational mastitis fails to show clinical defervescence and symptom improvement after 48 to 72 hours of appropriate oral antibiotic therapy, suspect a breast abscess. Order a diagnostic breast ultrasound immediately to identify fluid collections requiring ultrasound-guided needle aspiration.