Principles of Obstetrics Flashcards
what are some maternal causes of dystocia (5)
1) abnormal pelvis size or fracture
2) abnormal cervix (ringwomb)
3) uterine prolapse
4) uterine inertia
5) uterine torsion
what commonly causes failure of cervical dilation in:
1) sheep
2) cows
1) ringwomb
2) uterine torsion, or dead calf
how does ringwomb present in sheep and is there a genetic link
fetal membranes hanging from vulva; yes
what is uterine inertia and what are primary and secondary causes
inability of the uterus to produce contractions
primary: hypocalcemia, overstretching (hydrops, multiple fetuses)
secondary: exhaustion of the myometrium after prolonged and unsuccessful delivery attempt
what are some fetal causes of dystocia
1) fetal-maternal disproportion
2) fetal malalignment
3) multiple fetuses
4) fetal monsters
what is the most common cause of dystocia in cattle and what breed is this most associated with
fetal-maternal disproprtion; double-muscled breeds like Belgian blue
when does fetal-maternal disproportion commonly occur in dogs
when only a single pup that can grow too big for pelvis
what is the most common cause of dystocia in horses (and alpacas)
fetal malalignment
a calf is born with spinal curvature, unfused thoracic and abdominal walls and ankylosis
what is the diagnosis?
schistosomus reflexus
a calf is born with vertebral agenesis and arthrogryposis, flexure and ankylosis of the hindlimbs, no vertebrae caudal to the thorax, and a flat pelvis
the front half is relatively normal
what is the diagnosis?
perosomus elumbus
what is an autosomal recessive trait that is common in angus breeds
neuropathic hydrocephalus
what equine breeds are commonly associated with hydrocephalus and why
Belgian and Friesian horses; autosomal recessive mutation in B3GALNT2
what are 2 common causes of dystocia in dogs
1) fetal anasarca (associated with bulldogs)
2) fetal ascites (associated with organ abnormalities)
what is the most common cause of dystocia in cows
fetopelvic disproportion
what is the most common cause of dystocia in mares
fetal malalignment (most commonly head or limb deviation)
what is the most common cause of dystocia in the bitch
uterine inertia
what is the most common cause of dystocia in the queen
uterine inertia
what is the most common cause of dystocia in the ewe
fetal malalignment (often complicated with multiple fetuses)
what is the most common cause of dystocia in the ewe
fetal malalignment
what is the most common cause of dystocia in the sow
uterine inertia, followed by fetal malalignment
what three terms are used to describe the fetal alignment
- presentation
- position
- posture
presentation describes
the relative association of the long axis of the fetus with the maternal birth canal
what is normal presentation
anterior longitudinal (posterior longitudinal also normal in cows)
how can you tell whether the fetus is presenting in anterior or posterior longitudinal
anterior: the fetlock and carpus joints bend in the same direction
posterior: the fetlock and hock joints bend in opposite directions
what is an additional test besides palpation of joints that you can use to determine the presentation
anterior: palmar aspects of hooves point down; feel for head
posterior: plantar aspects of hooves point up; feel for tail
unless the fetus is upside down, always use palpation first
T/F posterior presentation is normal in cows but usually requires assistance
T
what is position
describes the surface of the maternal birth canal to which the dorsal aspect of the fetus is aligned
what is normal position
dorsal-sacral
what is posture
describes the disposition of the fetal head, neck and limbs
what is normal posture
extended neck and limbs
what is normal presentation, posture and positioning (use horses as an example)
anterior longitudinal, dorsal sacral, extended head and limbs
describe breech
posterior longitudinal with bilateral hip flexion
describe two types of abnormal presentation
transverse (dorsal or ventral) and vertical (dog sitting)
a mare is foaling and delivery appears normal (two toes and a nose) and then suddenly stops
what do you expect is happening
the baby is malpositioned and is in vertical presentation (dog sitting)
what is abnormal position
dorso-pubic; right or left dorsal-ilial
what are some examples of abnormal posture
lateral deviation of the head and neck; uni or bilateral carpal flexion, ventroflexion of the head (vertex); uni or bilateral shoulder flexion
what abnormal posture commonly causes rectovaginal fistulas
foot nape
T/F breech and posterior longitudinal, dorso-sacral with bilateral hock flexion are the same thing
F
breech: posterior longitudinal, dorso-sacral with bilateral hip flexion
not the same as bilateral hock flexion
you are presented a mare with dystocia and all you can see is the foals head
what is the likely posture of the foal
we know the foal is anterior longitudinally presented and dorso-sacral position
posture could be either bilateral shoulder flexion or bilateral carpal flexion
what do you want to assess on your initial exam of a dystocia
1) history (gather on way to farm)
2) general physical exam
3) cervix dilation
4) torsion?
5) fetal viability
6) fetal number
7) uterine tears
8) pelvic size/abnormalities
9) presentation, position and posture
what is the rule of 3
must see two limbs and a head present to pull
when dealing with dystocia we want to be as ________ as possible and be as ________ as possible
be as aseptic as possible and be as lubey as possible
where do you give an epidural in large animals with dystocia
sacro-coccygeal or C1-C2
why do we give epidural
reduces straining to help with extraction of the fetus (may result in more work for us though as we will need more assistance)
what lube do you NOT want to use in a dystocia and why
polymer lube; it is linked to acute deaths, and if it goes peritoneal causes hemolysis, peritonitis, renal failure and death
how do we most commonly assess fetal viability
fetal reflexes, also heartbeat, ECG or ultrasound can be used
how do fetal reflexes dissapear
from peripheral to central
how do we test fetal reflexes
1) interdigital claw
2) swallowing
3) eyeball (disappears last)
what fetal reflex is not consistent
anal
what is diagnostic traction
when you bring the head and two limbs into the birth canal with chains and see if you can make progress
what are good signs when you perform diagnostic traction
- hooves out with straining and in when straining stops
- fetlocks/hocks can be extended a hand’s width past the vulva
what are bad signs when you perform diagnostic traction
1) prolonged labour and head still not in pelvis
2) head goes back in when you start pulling the legs
3) forelimbs crossed
4) volar surfaces of hooves directed medially
what are the 3 principles of fetal repositioning
1) control
2) repulsion
3) rotation
how do we use rotation to reposition the fetus
1) bring distal limb in medially
2) rotate joint laterally
how do you place calving chains
with a double half-hitch; one hitch above the fetlock, one below on the pastern
T/F the fetal hooves have protective structures so it is not necessary to use any additional caution on the hooves
F; need to cup to prevent damage as we are correcting
how do you prevent hiplock
rotate the fetus 45 degrees through the widest angle of the pelvis
what are the 4 options for resolution of dystocia
1) assisted vaginal delivery (standing)
2) controlled vaginal delivery (anesthetized)
3) fetotomy
4) c-section
how do we perform assisted vaginal delivery
1) correct position
2) deliver in a downward arc
3) walk fetus through birth canal one forelimb in front of the other
T/F assisted vaginal delivery can be performed with or without epidural and sedation
T
how much force is needed to deliver a calf
70kg
T/F controlled vaginal delivery can be performed with or without sedation or epidural
F: it is performed under general anesthesia
what is a benefit of controlled vaginal delivery compared to assisted vaginal delivery
you can have members of the team preparing for c-section or fetotomy while you are working on the CVD
when you are called to the field for a dystocia and do an initial evaluation you determine the foal is alive; what is your next series of steps and timeline
1) determine if the foal can be delivered vaginally (do diagnostic traction)
2) if diagnostic traction confirms foal cannot be pulled -> c-section
3) if diagnostic traction confirms foal can be pulled -> spend 10 minutes on assisted vaginal delivery
4) if assisted vaginal delivery does not work -> spend 15 minutes on controlled vaginal delivery
5) if controlled vaginal delivery does not work -> c-section
you are called in for a dystocia and on initial assessment determine the foal is dead. what is your next series of steps and timeline
1) may decide to move on directly to fetotomy if you perform diagnostic traction and the foal cannot be delivered vaginally
2) if diagnostic traction confirms vaginal delviery is possible -> spend 10 minutes on assisted vaginal delivery
3) if AVD fails -> spend 15 minutes on controlled vaginal delivery
4) if CVD fails -> consider C-section or fetotomy