I would say three quarts would be categorized as a large enema. I have found references to four-quart enemas being categorized as a large enema in The Modern Medical Counselor from the late 40's to early 50's, but I am unable to locate any actual nursing protocols calling for a four-quart enema.
Historical obstetric context
In labor and delivery, 1,000–2,000 mL enemas were more common to avoid excessive discomfort or uterine irritation.
However, some hospital and nursing protocols (early–mid 20th century) ordered up to 3,000 mL if:
The patient was severely constipated
A “high and hot enema” was believed to stimulate uterine contractions via bowel reflexes
Complete colon cleansing was desired for hygiene reasons in pre-delivery preparation
References supporting this
Gray’s Manual of Nursing Practice (early editions)
“The high enema may range from 2,000 to 3,000 mL, administered slowly to cleanse as far as the ascending colon. In obstetric patients, caution is used to avoid excessive uterine stimulation.”
Maternal and Child Health Nursing (1940s–1950s editions)
“High enemas of 2–3 quarts were occasionally used to clear the colon thoroughly, though in laboring women 1–2 quarts sufficed.”
Dorland’s Illustrated Medical Dictionary (historical editions)
Defines high enema as one that “introduces up to 3,000 mL of fluid to cleanse the entire colon.”
Protocols using up to 3,000 mL (3 quarts) for a “full high enema”
“Full high enema” refers to large-volume enemas intended to cleanse the entire colon, not just the rectum and sigmoid. These were administered with:
Volume: Up to 3,000 mL (3 quarts)
Solution: Warm water, soapsuds, or saline
Temperature: Typically 105–110°F (40.5–43.3°C) for stimulation without mucosal scalding
Height: Administered from 24–36 inches or higher to create sufficient gravity flow
Hope this provides some clarification.