Physiological changes in pregnancy:
- Increase in CO and HR
- Reduced BP, vasodilation
- Reduction in venous return and subsequent hypotension in supine position with caval compression – elevate right side during surgery
- Increased oxygen consumption up to 40 %
- Increase in circulating plasma volume up to 50 %
- 10 x risk of VTE due to venous stasis secondary to IVC compression as well as increases in plasma concentrations of procoagulants
Physiological changes leading to hydronephrosis:
- Increased renal blood flow, with GFR increasing by 50 % and increased urine output
- Mechanical compression of pelvis and retroperitoneum causing dilation of collecting systems, right > left
- Higher levels of progesterone causes smooth muscle relaxation
- Right sided more common due to gravid uterus dextro-rotation, left side protected by gas filled sigmoid, and potentially right ureter compressed by dilated right gonadal vein which crosses
- Right sided dilation in up to 90 % by end of third trimester
- Historically average 15 mm right sided pelvicalyceal dilation, 5 mm on left
Principles of operating on pregnant women:
- Defer operating if possible – but – do not withhold necessary surgery just because a woman is pregnant
- Multidisciplinary decision making with obstetricians and anaesthetics
- Consider elevating right side to reduce caval compression which reduces venous return
- Remember significantly higher VTE risk in pregnant women.
- Foetal Doppler/monitoring is usually used pre and post-operatively to exclude complication and reassure mother
- GA can theoretically risk pre-term labour although these risks are small in absolute terms
- Avoid excess stimulation of cervix during prep
- Consider omitting fluoroscopy, using ultrasound to check stent placement if available
- Second trimester is optimal time to operate (avoid risk of inducing labour)
- No anaesthetic agents seem to have teratogenic effects
- Operations should be done at hospitals with appropriate neonatal and obstetric services, and obstetricians should be aware the procedure is happening and available if needed
- Avoid high pressures if operating laparoscopically (aim < 15 mm Hg).
Principles of imaging during pregnancy:
- Follow ALARA principles
- Risk of stochastic effects (no-threshold linear model)
- Radiation doses < 50 mGy considered largely safe
- Mainly studied risk is leukaemia – 1.5 – 2 x relative risk with 10 – 20 mGy (background risk 1 in 3000)
- Risk would be highest during first semester and organogenesis
- Can use shielding, omit fluoro, ultrasound/MRI instead of CT
Ultrasound is first line imaging modality
- Operator dependent
- Renal pelvis, proximal ureteric and VUJ stones may be visible; not mid ureteric
- Ureteric jet may be useful
- Resistance index
MRI is second line – indicated if concerns for ureteric stone not elucidated on ultrasound
- No radiation
- Non contrast
- May be difficult to access
- Stones visualised as filling defects in the high intensity signal of urine on T2
- MRI contrast/Gad controversial in pregnancy.
CT has best sensitivity and specificity but its use is limited by radiation dose, however:
- Radiation exposure from non contrast CT is much lower than exposure associated with foetal harm
- Radiation doses < 50 mGy considered safe in pregnancy
- Risk minimised in third trimester
- Should be used as last line imaging
- Contrast crosses placenta, but no known teratogenic properties. Iodinated – ?effect of thyroid development.
Haematuria in pregnancy
- 20 % microscopic haematuria on dipstick in asymptomatic pregnancy
- Aetiologies include:
- UTI / infection
- Stones
- Medical renal disease
- Medications
- Trauma
- Tumours – RCC, TCC
- Preeclampsia
- Placenta percreta
Preeclampsia – hypertension and proteinuria, with microhaematuria 2- 8 x normal level.
Stones in pregnancy
Variable incidence depending on source – between 1 in 200 and 1 in 1500.
Overall incidence appears similar to non-pregnant women of similar ages.
Most patients present in second and third trimester.
Physiological changes in pregnancy contributing to stone formation:
- Increased vitamin D levels (placental production) -> hypercalciuria
- Increased renal blood and GFR -> increased filtered solute load
- Increased urinary concentration of stone inhibitors (citrate and Mg)
- Increased urinary calcium and glucose
- Increased urine volumes (preventative)
- Stasis and increased renal pelvis pressures due to physiological hydronephrosis
- Elevated urine pH (calcium phosphate stones most common in pregnant women)
Management principles:
- Multidisciplinary care shared with obstetrician
- Consider alternate diagnoses as causes of pain (appendicitis, pyelonephritis, colitis)
- Observation and conservative management should be first line in the absence of infection and uncontrolled pain
- Attempt to avoid risks to pregnancy – i.e., ionising radiation, risks of anaesthesia, risks of sepsis
- Management should be undertaken in a centre with both urological and obstetric capability
Investigation of women with loin pain:
- History – loin pain, symptoms of infection, history of UTIs, haematuria and urinary symptoms, obstetric history and complicating features
- Examination – vital signs, flank tenderness, health of child
- Blood tests including renal function
- Urine analysis – blood, nitrites, leukocytes
Management of symptomatic stones
In the presence of infection -> ureteric stent.
In the presence of symptoms:
- Conservative management preferred in the absence of strong indications for intervention
- Alpha blockers have not been studied in pregnancy
- 70 – 80 % stones can be successfully managed conservatively
- Stent (or nephrostomy) which can be maintained during pregnancy, then proceeding to definitive ureteroscopy after pregnancy
- Primary ureteroscopy and laser of stone
ESWL is contra-indicated.
PCNL has only limited evidence and should rarely be needed in individualised cases in experienced centres.
Nephrostomy is a reasonable alternative to stenting:
- Can be done without GA
- Can be done with radiation under ultrasound, and changed in the same way without GA or ultrasound
Ureteric stents tend to encrust quicker in pregnancy due to hypercalciuria and hyperuricosuria:
- Stents often poorly tolerated with significant analgesia requirements
- Reduced quality of life
- May require frequent changes 4 – 8 weekly (with risks associated each time)
- May be nidus for bacteriuria and subsequent complicated UTIs/sepsis
Medications in general
NSAIDs are generally contra-indicated in pregnancy, especially after 20 – 30 weeks.
Categories:
- A – safe, widely taken with no increase malformations or harmful effects
- Panadol, cefalexin,
- B1 – has been taken by limited number of pregnant women without increase in harm, studies in animals have not shown problems
- Ceftriaxone, piptaz
- B2 – limited number of pregnant women without increase in harm, lacking or inadequate animal studies without problems
- Tamsulosin, prazosin, meropenem
- B3 – limited number of pregnant women without increase in harm, animal studies suggest possible damage of unclear significance in humans
- C – drugs which have caused or suspected of causing harmful effects which may be reversible
- Ibuprofen, indomethacin, oxycodone, tramadol
- D – have caused or suspected to have caused harmful effects like malformations or irreversible damage
- Gentamicin
- X – very high risk of causing permanent damage, do not use if possibility of pregnancy
- Thalidomide
Pregnancy in spina bifida
- Generally normal fertility with 70 % pregnancies successful
- Often have latex allergies
- Multidisciplinary – MFM, neonatology, ortho, high risk obstetrics, anaesthetics, neurosurgeons
- 1 – 8 % risk of neural tube defects in children of those with NTD
- Patients have usually had an array for reconstructive urological surgery
Potential issues include:
- Renal function is at risk – usually affected from start, any UTIs, ureteric compression, hypertension etc may contribute to further decline
- High risk of stones – subsequent UTIs, obstruction
- High risk of UTIs during pregnancy, consideration of prophylaxis
- Potential threat to vascular supply of augmented or reconstructed bowel segments (due to compression by gravid uterus or surgery)
- Compression or prolapse of catheterisable channels
- Choice of delivery – influenced by previous surgical interventions, foetal health and presentation, and any other underlying anatomic issues
- Potential threat to continence after delivery especially if has required bladder neck recon or SUI procedures in past
- VP shunt if in situ could be compressed during pregnancy or infected during operations
- Narrow bony pelvis or hips could preclude vaginal delivery
- Depending on patients’ sensation and motor function – may not be able to detect or voluntarily push during labour
If doing C-section in patient with augment/neobladder – ensure drainage of bladder pre-op, high ‘classical’ c-section, mesentery to bowel segment should be identified and kept away from uterus, should be done electively if at all possible.