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Expected genitourinary changes during pregnancy

Renal function

• GFR increases 40-65% due to increased blood flow
• Hyponatremia: mild (4-5mmol/L below baseline) secondary to lower threshold for ADH secretion
• Kidneys enlarge ~1cm
• Pelvicalyceal dilation: seen in ~90%, 15mm on R side and 5mm on L
• Ureteral dilation due to smooth muscle relaxation and uterine compression (starts during 2nd month, worse on R side)
• Hydronephrosis: usually physiologic, attempt conservative therapy (analgesia, positioning, IV fluids) if symptomatic

Urinalysis findings

• Glucosuria: intermittent normal, but persistent is concerning for diabetes
• Proteinuria expected up to 300mg (albuminuria up to 30mg)
• Calciuria: doubles during pregnancy but serum ionized levels are unchanged
• Hematuria: seen in up to 20%, usually benign due to increased vascularity, but consider other causes if persistent, unclear if associated with preeclampsia

Diagnostic and treatment considerations

Imaging considerations

• Exposure: should not exceed 50mGy or 10 rads fetal exposure
• Timing: most concerning during first trimester due to organogenesis and rapid cell division, decreased radiation sensitivity during 2nd/3rd trimesters but potential increased risk for childhood cancers
• Type: US and MR imaging have no associated risks, XR, CT, and NM studies should be offered with understanding of potential risk, but exposure is lower than harmful level
• Contrast: minimal overall proven risk, but only use if "benefits outweigh risks"
• Intraop use: use shielding and lower doses
• Fetal risks: mutagenesis (0.1-0.4% risk per rad of fetal exposure), developmental delay (0.4% risk per rad of fetal exposure), childhood cancer (~0.05% risk per rad of fetal exposure), teratogenetis (rare below 10rads), spontaneous abortion (potentially before implantation, otherwise rare below 10rads)

Operative considerations

• Anesthetic agents: not proven to have any teratogenic effects
• Considerations: indicated surgery must be recommmended regardless of pregnancy status, nonurgent surgery should be performed during 2nd trimester - preterm contractions and spontaneous abortion are least likely
• Intraop tips: OB provider with C-section capabilities should be available, fetal heart monitoring recommended, venous return may be decreased due to IVC compression, can perform open or laparoscopic surgery during pregnancy, insufflate to 10-15mmHg
• Preterm delivery: occurs 16% during 3rd trimester surgeries, including 10% ureteroscopy
• Hematologic changes: patients become anemic and at higher risk for coagulopathy (venous stasis in legs + increased clotting factors)

Bacteruria in Pregnancy

Considerations

• Prevalence: 2-7%, similar to general population
• Resolution: less likely to spontaneously resolve compared to non-pregnant patients
• Timing: pyelonephritis most common in 3rd trimester, occurs 15-45% patients with untreated bacteruria
• Management: treatment of asymptomatic bacteruria decreases morbidity and complications, screen for bacteruria at 12-16 weeks, admit patients with pyelonephritis for treatment

Antibiotics in pregnancy

• Penicillins: ampicillin 500mg QID, amoxicillin 250mg TID, penicillin 500mg QID
• Cephalosporins: cephalexin 500mg QID, cefaclor 500mg QID
• Nitrofurantoin: 100mg BID (avoid after 35 weeks due to neonatal hemolytic anemia)
• Other antibiotics: aminoglycosides, clindamycin, erythromycin (after 12wks, risk of cholestatic jaundice)

Antibiotics to AVOID

• Fluoroquinolones: cause cartilage damage
• Chloramphenicol: cause gray baby syndrome
• Trimethoprim: inhibit folic acid metabolism
• Tetracyclines: inhibit new bone growth

Stones

Pathophys

• Incidence: occur in 1:200-1:1500 pregnancies, similar incidence of laterality despite more prevalent right sided hydronephrosis
• Complications: increases risk for preterm delivery, preeclampsia, placenta previa, and PPROM
• Stone type: calcium phosphate more common due to combination hypercalciuria and elevated pH
• UTI: consider looking for a stone if recurrent infections with urease-producing organisms

Presentation

• Symptoms: flank pain most common, then hematuria and UTI
• US: first line imaging, may show resistive index > 0.7, RI differential > 0.06, ureteral dilation past iliac vessels (normally not dilated), or absence of ureteral jets
• Transvaginal US: may be more accurate for diagnosing distal stones
• CT: consider for surgical planning or if US non-diagnostic, discuss risks/benefits but overall radiation dose is negligible
• MRU: gadolinium considered safe in pregnancy, can consider to avoid radiation dose

Management

• Observation: 50-80% will spontaneously pass with hydration and analgesia
• NSAIDs contraindicated in pregnancy (causes closure of ductus arteriosus)
• a-blockers: safe for pregnancy, can also use tylenol and narcotics (except codeine)
• Acute intervention: stents and PCNs can be used but rapidly encrust and require exchange q4-6 weeks, may also increase risk for preterm labor
• Ureteroscopy: best performed during 2nd trimester (lowest anesthesia risk), no difference in complications from nonpregnant patients, preterm labor rates ~4%
• Other options: ESWL contraindicated, avoid PCNL due to prolonged anesthesia and XRT exposure

GU conditions that may complicate pregnancies

Myelomeningocele

• Family planning: usually normal fertility, 70% successful conceptions, use latex-free condoms and other devices
• Fetal risks: neural tube defect in offspring is 1%-15% (if both parents affected)
• Maternal risks: pre-existing renal insufficiency exacerbated during pregnancy, ncreased risk of stones, pyelonephritis, urinary diversion at risk for ischemia, stenosis, prolapse
• Delivery: avoid vaginal delivery in narrow pelvis, AUS, bladder neck reconstruction, contracted hips, cautious vaginal delivery if prolapse, ureterosigmoidostomy, malpresentation, cautious C-section if VP shunts, intestinal incorporation into GU tract (avoid pedicle)

Bladder exstrophy

• Anatomy: vaginal introitus often narrow and stenotic with horizontal lie
• Prolapse: common (18-30%) due to poor apical support, consider management with bed rest and pessary
• Risks: increased spontaneous abortion risk (35%), ncreased preeclampsia risk (32%), higher if prior renal insufficiency
• Delivery: vaginal delivery difficult, usually undergo C-section

Bladder augmentation

• Pregnancy test: urine exposure to bowel mucosa may give false positive pregnancy test reading
• Catheterization: may be more difficult due to change of channel angle, usually blood supply stretches without issue
• Infection: increased pyelonephritis risk (16-18%), consider antibiotic prophylaxis during pregnancy (no consensus)
• Delivery: perform C-section as high-midline or paramedian incision to avoid injuring reservoir or pedicles, consider catheterizing channels during C-section to assist with identification, complications occur in up to 40%

GU malignancies

• Contrast: if enhanced images required, CT contrast has reportedly lower risks than MR contrast
• AML: increased risk for rupture during pregnancy, consider observation with embolization (risk of premature labor), surgery reserved for urgent indications
• Renal biopsy: consider if it would affect decision to treat or observe during pregnancy
• Renal cancer management: (partial) nephrectomy after delivery (T1a), nephrectomy during pregnancy (T1b-T2, can wait if 3rd trimester), surgery or systemic therapy immediately (T3-T4, M1)
• TURBT: can perform at any stage to obtain tissue for bladder tumor diagnosis, okay to delay NMIBC treatment until after pregnancy
• Bladder cancer management: TURBT +/- intravesical chemo (Ta-T1), NAC during pregnancy + cystectomy after delivery (T2-T4, N1), palliative chemo (M1)

Transplant

• Timing: less risk for graft loss after 1-2yr, pregnancy > 5yr after transplant has potential risk for permanent reduction in renal function
• Ideal conditions: Cr < 1.5, minimal proteinuria, no rejection in past year, controlled HTN, stable medications
• Transplant risks: rejection less likely, no change in graft survival/function
• Fetal risks: IUGR, premature labor, infections
• Safer immunosuppresive drugs: azathioprine, cyclosporine, steroids, tacrolimus
• Monitoring: higher risk for gestational HTN and DM, hydronephrosis, proteinuria, infection
• Delivery: no contraindication to vaginal delivery, consider stress dose of steroids

GU conditions that can occur during pregnancy

Placenta percreta

• Prevalence: 1 in 500-2500 pregnancies, more common if prior C-sections
• Presentation: hematuria occurs in 25%
• Diagnosis: US and MR have similar rates of sensitivity/specificity, can consider cystoscopy but do not biopsy (risk for bleeding)
• Concerns: 29% ureteral injury rate (compared to 5% for hysterectomy), may require 20-40U blood products, mortality rates 9.5% (mother) and 24% (baby)
• Intraop findings: loss of bladder/uterine plane, dilated vessels overlying bladder serosa
• Gyn management: consider planned C-section at 34wks w/ hysterectomy, posterior approach to hysterectomy (anterior approach risks severe bleeding due to lack of vascular control), retract ureters laterally and uterus medially
• Uro management: recommend prophylactic stent placement (decreases ureteral injury risk), removal of placenta from bladder (do not leave in-situ), 2-layer bladder closure, omental interposition, may require ureteral reimplant or partial cystectomy

Incarcerated uterus

• Prevalence: 1 in 3000 pregnancies, more likely if fibroids, endometriosis, adhesions
• Pathophys: 14% of women have a retroverted uterus, normally flips to anteverted as uterus grows during pregnancy but can occasionally become trapped by sacrum and compress urethra, causing retention
• Presentation: retention, dysuria, constipation
• Complications: renal injury/failure, bladder rupture, premature membrane rupture, miscarriage
• Management: place catheter, pelvic exam to confirm retroversion (cervix behind pubic symphysis, fundus nonpalpable), reposition with knee-chest positioning, manual reduction, colonic insufflation via colonoscopy, amnioreduction, laparoscopy/laparotomy

Renal rupture

• Risk factors: rare, but may be related to prior trauma, surgery, or stones
• Cancer risk: can occur in presence of tumors, perform thorough evaluation
• Management: nephrectomy if parenchymal rupture, stent/PCN if collecting system rupture

Postpartum incontinence

• Pudendal nerve injury: due to stretch/compression, can lead to urinary and fecal incontinence
• Pelvic floor muscle injury: due to injury during delivery
• Management: usually resolves within 3 months, behavioral training, pelvic floor training